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Question Number 21423 Answers: 1 Comments: 0

Prove that n^4 + 4^n is composite for all integer values of n greater than 1.

$$\mathrm{Prove}\:\mathrm{that}\:{n}^{\mathrm{4}} \:+\:\mathrm{4}^{{n}} \:\mathrm{is}\:\mathrm{composite}\:\mathrm{for}\:\mathrm{all} \\ $$$$\mathrm{integer}\:\mathrm{values}\:\mathrm{of}\:{n}\:\mathrm{greater}\:\mathrm{than}\:\mathrm{1}. \\ $$

Question Number 21412 Answers: 0 Comments: 0

The atomic masses of ′He′ and ′Ne′ are 4 and 20 a.m.u., respectively. The value of the de Broglie wavelength of ′He′ gas at −73°C is “M” times that of the de Broglie wavelength of ′Ne′ at 727°C ′M′ is

$$\mathrm{The}\:\mathrm{atomic}\:\mathrm{masses}\:\mathrm{of}\:'\mathrm{He}'\:\mathrm{and}\:'\mathrm{Ne}'\:\mathrm{are} \\ $$$$\mathrm{4}\:\mathrm{and}\:\mathrm{20}\:\mathrm{a}.\mathrm{m}.\mathrm{u}.,\:\mathrm{respectively}.\:\mathrm{The} \\ $$$$\mathrm{value}\:\mathrm{of}\:\mathrm{the}\:\mathrm{de}\:\mathrm{Broglie}\:\mathrm{wavelength}\:\mathrm{of} \\ $$$$'\mathrm{He}'\:\mathrm{gas}\:\mathrm{at}\:−\mathrm{73}°\mathrm{C}\:\mathrm{is}\:``\mathrm{M}''\:\mathrm{times}\:\mathrm{that}\:\mathrm{of} \\ $$$$\mathrm{the}\:\mathrm{de}\:\mathrm{Broglie}\:\mathrm{wavelength}\:\mathrm{of}\:'\mathrm{Ne}'\:\mathrm{at} \\ $$$$\mathrm{727}°\mathrm{C}\:'\mathrm{M}'\:\mathrm{is} \\ $$

Question Number 21411 Answers: 0 Comments: 0

The critical temperature of water is higher than that of O_2 because the H_2 O molecule has (a) fewer electrons than O_2 (b) two covalent bonds (c) V-shape (d) dipole moment.

$$\mathrm{The}\:\mathrm{critical}\:\mathrm{temperature}\:\mathrm{of}\:\mathrm{water}\:\mathrm{is} \\ $$$$\mathrm{higher}\:\mathrm{than}\:\mathrm{that}\:\mathrm{of}\:\mathrm{O}_{\mathrm{2}} \:\mathrm{because}\:\mathrm{the} \\ $$$$\mathrm{H}_{\mathrm{2}} \mathrm{O}\:\mathrm{molecule}\:\mathrm{has} \\ $$$$\left({a}\right)\:\mathrm{fewer}\:\mathrm{electrons}\:\mathrm{than}\:\mathrm{O}_{\mathrm{2}} \\ $$$$\left({b}\right)\:\mathrm{two}\:\mathrm{covalent}\:\mathrm{bonds} \\ $$$$\left({c}\right)\:\mathrm{V}-\mathrm{shape} \\ $$$$\left({d}\right)\:\mathrm{dipole}\:\mathrm{moment}. \\ $$

Question Number 21422 Answers: 1 Comments: 3

Find all integer values of a such that the quadratic expression (x + a)(x + 1991) + 1 can be factored as a product (x + b)(x + c) where b and c are integers.

$$\mathrm{Find}\:\mathrm{all}\:\mathrm{integer}\:\mathrm{values}\:\mathrm{of}\:{a}\:\mathrm{such}\:\mathrm{that} \\ $$$$\mathrm{the}\:\mathrm{quadratic}\:\mathrm{expression} \\ $$$$\left({x}\:+\:{a}\right)\left({x}\:+\:\mathrm{1991}\right)\:+\:\mathrm{1}\:\mathrm{can}\:\mathrm{be}\:\mathrm{factored} \\ $$$$\mathrm{as}\:\mathrm{a}\:\mathrm{product}\:\left({x}\:+\:{b}\right)\left({x}\:+\:{c}\right)\:\mathrm{where}\:{b}\:\mathrm{and} \\ $$$${c}\:\mathrm{are}\:\mathrm{integers}. \\ $$

Question Number 21426 Answers: 1 Comments: 0

given (√(2017x^2 + 4034x + 17)) + (√(2017x^2 + 4034x − 3)) = 10, then find the value x^2 + 2x.

$$\mathrm{given}\:\sqrt{\mathrm{2017}{x}^{\mathrm{2}} \:+\:\mathrm{4034}{x}\:+\:\mathrm{17}}\:+\:\sqrt{\mathrm{2017}{x}^{\mathrm{2}} \:+\:\mathrm{4034}{x}\:−\:\mathrm{3}}\:=\:\mathrm{10}, \\ $$$$\mathrm{then}\:\mathrm{find}\:\mathrm{the}\:\mathrm{value}\:{x}^{\mathrm{2}} \:+\:\mathrm{2}{x}. \\ $$

Question Number 21406 Answers: 0 Comments: 2

Find the number of ways in which n distinct balls can be put into three boxes so that no two boxes remain empty.

$$\mathrm{Find}\:\mathrm{the}\:\mathrm{number}\:\mathrm{of}\:\mathrm{ways}\:\mathrm{in}\:\mathrm{which}\:{n} \\ $$$$\mathrm{distinct}\:\mathrm{balls}\:\mathrm{can}\:\mathrm{be}\:\mathrm{put}\:\mathrm{into}\:\mathrm{three} \\ $$$$\mathrm{boxes}\:\mathrm{so}\:\mathrm{that}\:\mathrm{no}\:\mathrm{two}\:\mathrm{boxes}\:\mathrm{remain} \\ $$$$\mathrm{empty}. \\ $$

Question Number 21405 Answers: 1 Comments: 0

Four dice are rolled. The number of ways in which at least one die shows 3, is

$$\mathrm{Four}\:\mathrm{dice}\:\mathrm{are}\:\mathrm{rolled}.\:\mathrm{The}\:\mathrm{number}\:\mathrm{of}\:\mathrm{ways} \\ $$$$\mathrm{in}\:\mathrm{which}\:\mathrm{at}\:\mathrm{least}\:\mathrm{one}\:\mathrm{die}\:\mathrm{shows}\:\mathrm{3},\:\mathrm{is} \\ $$

Question Number 21404 Answers: 1 Comments: 0

Prove that (6n)! is divisible by 2^(2n) .3^n .

$$\mathrm{Prove}\:\mathrm{that}\:\left(\mathrm{6}{n}\right)!\:\mathrm{is}\:\mathrm{divisible}\:\mathrm{by}\:\mathrm{2}^{\mathrm{2}{n}} .\mathrm{3}^{{n}} . \\ $$

Question Number 21401 Answers: 0 Comments: 0

∫_0 ^∞ ((xdx)/(e^x +1))=?

$$\underset{\mathrm{0}} {\overset{\infty} {\int}}\frac{{xdx}}{{e}^{{x}} +\mathrm{1}}=? \\ $$

Question Number 21398 Answers: 1 Comments: 0

∫_( 0) ^∞ (1/(1+e^x )) dx =

$$\underset{\:\mathrm{0}} {\overset{\infty} {\int}}\:\:\:\frac{\mathrm{1}}{\mathrm{1}+{e}^{{x}} }\:{dx}\:= \\ $$

Question Number 21394 Answers: 2 Comments: 0

Question Number 21392 Answers: 1 Comments: 0

Question Number 21390 Answers: 0 Comments: 0

∫_0 ^1 ((x^7 − 1)/(ln x)) dx

$$\underset{\mathrm{0}} {\overset{\mathrm{1}} {\int}}\:\:\frac{{x}^{\mathrm{7}} \:−\:\mathrm{1}}{\mathrm{ln}\:{x}}\:{dx} \\ $$

Question Number 21388 Answers: 0 Comments: 4

A block of mass m is connected with another block of mass 2m by a light spring. 2m is connected with a hanging mass 3m by an inextensible light string. At the time of release of block 3m, find tension in the string and acceleration of all the masses.

$$\mathrm{A}\:\mathrm{block}\:\mathrm{of}\:\mathrm{mass}\:{m}\:\mathrm{is}\:\mathrm{connected}\:\mathrm{with} \\ $$$$\mathrm{another}\:\mathrm{block}\:\mathrm{of}\:\mathrm{mass}\:\mathrm{2}{m}\:\mathrm{by}\:\mathrm{a}\:\mathrm{light} \\ $$$$\mathrm{spring}.\:\mathrm{2}{m}\:\mathrm{is}\:\mathrm{connected}\:\mathrm{with}\:\mathrm{a}\:\mathrm{hanging} \\ $$$$\mathrm{mass}\:\mathrm{3}{m}\:\mathrm{by}\:\mathrm{an}\:\mathrm{inextensible}\:\mathrm{light}\:\mathrm{string}. \\ $$$$\mathrm{At}\:\mathrm{the}\:\mathrm{time}\:\mathrm{of}\:\mathrm{release}\:\mathrm{of}\:\mathrm{block}\:\mathrm{3}{m},\:\mathrm{find} \\ $$$$\mathrm{tension}\:\mathrm{in}\:\mathrm{the}\:\mathrm{string}\:\mathrm{and}\:\mathrm{acceleration} \\ $$$$\mathrm{of}\:\mathrm{all}\:\mathrm{the}\:\mathrm{masses}. \\ $$

Question Number 21377 Answers: 0 Comments: 0

Balls are dropped from the roof of a tower at a fixed interval of time. At the moment when 9th ball reaches the ground the nth ball is (3/4)th height of the tower. What is the value of n?

$$\mathrm{Balls}\:\mathrm{are}\:\mathrm{dropped}\:\mathrm{from}\:\mathrm{the}\:\mathrm{roof}\:\mathrm{of}\:\mathrm{a} \\ $$$$\mathrm{tower}\:\mathrm{at}\:\mathrm{a}\:\mathrm{fixed}\:\mathrm{interval}\:\mathrm{of}\:\mathrm{time}.\:\mathrm{At}\:\mathrm{the} \\ $$$$\mathrm{moment}\:\mathrm{when}\:\mathrm{9th}\:\mathrm{ball}\:\mathrm{reaches}\:\mathrm{the} \\ $$$$\mathrm{ground}\:\mathrm{the}\:{n}\mathrm{th}\:\mathrm{ball}\:\mathrm{is}\:\left(\mathrm{3}/\mathrm{4}\right)\mathrm{th}\:\mathrm{height} \\ $$$$\mathrm{of}\:\mathrm{the}\:\mathrm{tower}.\:\mathrm{What}\:\mathrm{is}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:{n}? \\ $$

Question Number 21366 Answers: 3 Comments: 0

Question Number 21357 Answers: 1 Comments: 0

Solve : log_(2x+3) x^2 < 1

$$\mathrm{Solve}\::\:\mathrm{log}_{\mathrm{2}{x}+\mathrm{3}} {x}^{\mathrm{2}} \:<\:\mathrm{1} \\ $$

Question Number 21356 Answers: 1 Comments: 0

Solve : (2^((3x−1)/(x−1)) )^(1/3) < 8^((x−3)/(3x−7))

$$\mathrm{Solve}\::\:\sqrt[{\mathrm{3}}]{\mathrm{2}^{\frac{\mathrm{3}{x}−\mathrm{1}}{{x}−\mathrm{1}}} }\:<\:\mathrm{8}^{\frac{{x}−\mathrm{3}}{\mathrm{3}{x}−\mathrm{7}}} \\ $$

Question Number 21355 Answers: 1 Comments: 0

Solve : ∣x^2 + 3x∣ + x^2 − 2 ≥ 0

$$\mathrm{Solve}\::\:\mid{x}^{\mathrm{2}} \:+\:\mathrm{3}{x}\mid\:+\:{x}^{\mathrm{2}} \:−\:\mathrm{2}\:\geqslant\:\mathrm{0} \\ $$

Question Number 21354 Answers: 0 Comments: 4

Solve : (√(2x + 5)) + (√(x − 1)) > 8

$$\mathrm{Solve}\::\:\sqrt{\mathrm{2}{x}\:+\:\mathrm{5}}\:+\:\sqrt{{x}\:−\:\mathrm{1}}\:>\:\mathrm{8} \\ $$

Question Number 21374 Answers: 0 Comments: 2

In how many ways can the letters of the word PATLIPUTRA be arranged, so that the relative order of vowels are consonants do not alter?

$$\mathrm{In}\:\mathrm{how}\:\mathrm{many}\:\mathrm{ways}\:\mathrm{can}\:\mathrm{the}\:\mathrm{letters}\:\mathrm{of}\:\mathrm{the} \\ $$$$\mathrm{word}\:\mathrm{PATLIPUTRA}\:\mathrm{be}\:\mathrm{arranged},\:\mathrm{so} \\ $$$$\mathrm{that}\:\mathrm{the}\:\mathrm{relative}\:\mathrm{order}\:\mathrm{of}\:\mathrm{vowels}\:\mathrm{are} \\ $$$$\mathrm{consonants}\:\mathrm{do}\:\mathrm{not}\:\mathrm{alter}? \\ $$

Question Number 21350 Answers: 0 Comments: 0

prove (√2) < log_8 19 < (3)^(1/3)

$$\boldsymbol{{prove}}\: \\ $$$$\:\sqrt{\mathrm{2}}\:<\:\boldsymbol{{log}}_{\mathrm{8}} \mathrm{19}\:<\:\sqrt[{\mathrm{3}}]{\mathrm{3}} \\ $$

Question Number 21342 Answers: 1 Comments: 0

Question Number 21341 Answers: 2 Comments: 0

the angle between the straight lines x^2 +4xy+3y^2 =0 is

$${the}\:{angle}\:{between}\:{the}\:{straight}\:{lines}\:{x}^{\mathrm{2}} +\mathrm{4}{xy}+\mathrm{3}{y}^{\mathrm{2}} =\mathrm{0}\:{is} \\ $$

Question Number 21321 Answers: 1 Comments: 0

The number of real solutions of the equation 4x^(99) + 5x^(98) + 4x^(97) + 5x^(96) + ..... + 4x + 5 = 0 is

$$\mathrm{The}\:\mathrm{number}\:\mathrm{of}\:\mathrm{real}\:\mathrm{solutions}\:\mathrm{of}\:\mathrm{the} \\ $$$$\mathrm{equation}\:\mathrm{4}{x}^{\mathrm{99}} \:+\:\mathrm{5}{x}^{\mathrm{98}} \:+\:\mathrm{4}{x}^{\mathrm{97}} \:+\:\mathrm{5}{x}^{\mathrm{96}} \:+ \\ $$$$.....\:+\:\mathrm{4}{x}\:+\:\mathrm{5}\:=\:\mathrm{0}\:\mathrm{is} \\ $$

Question Number 21319 Answers: 0 Comments: 0

If x, y, z are three real numbers such that x + y + z = 4 and x^2 + y^2 + z^2 = 6, then (1) (2/3) ≤ x, y, z ≤ 2 (2) 0 ≤ x, y, z ≤ 2 (3) 1 ≤ x, y, z ≤ 3 (4) 2 ≤ x, y, z ≤ 3

$$\mathrm{If}\:{x},\:{y},\:{z}\:\mathrm{are}\:\mathrm{three}\:\mathrm{real}\:\mathrm{numbers}\:\mathrm{such} \\ $$$$\mathrm{that}\:{x}\:+\:{y}\:+\:{z}\:=\:\mathrm{4}\:\mathrm{and}\:{x}^{\mathrm{2}} \:+\:{y}^{\mathrm{2}} \:+\:{z}^{\mathrm{2}} \:=\:\mathrm{6}, \\ $$$$\mathrm{then} \\ $$$$\left(\mathrm{1}\right)\:\frac{\mathrm{2}}{\mathrm{3}}\:\leqslant\:{x},\:{y},\:{z}\:\leqslant\:\mathrm{2} \\ $$$$\left(\mathrm{2}\right)\:\mathrm{0}\:\leqslant\:{x},\:{y},\:{z}\:\leqslant\:\mathrm{2} \\ $$$$\left(\mathrm{3}\right)\:\mathrm{1}\:\leqslant\:{x},\:{y},\:{z}\:\leqslant\:\mathrm{3} \\ $$$$\left(\mathrm{4}\right)\:\mathrm{2}\:\leqslant\:{x},\:{y},\:{z}\:\leqslant\:\mathrm{3} \\ $$

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