x^( 2) − 4x −1=0
α , β are roots
α^( 3) + 17β +5 =?
−−−solution−−−
α is root ⇒ α^( 2) −4α −1=0
⇒ α^( 2) = 4α +1 ✓
α^( 3) + 17β +5 = α . α^( 2) +17β +5
= α ( 4α +1 )+ 17β +5
= 4α^( 2) + α + 17β +5
= 4 (4α +1 )+α +17β +5=17(α+β)+9
= 17S +9= 17 (4 )+9=77
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