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Question Number 39879 by Rio Mike last updated on 12/Jul/18
let   p(x)= x^3  + 3x − 4  find α+β and   αβ
letp(x)=x3+3x4findα+βandαβ
Answered by MrW3 last updated on 12/Jul/18
p(x)= x^3  + 3x − 4=(x−1)(x^2 +Ax+B)  =x^3 +(A−1)x^2 +(B−A)x−B  ⇒B=4  ⇒A−1=0⇒A=1  ⇒B−A=4−1=3=^! 3    p(x)= x^3  + 3x − 4=(x−1)(x^2 +x+4)  =(x−1)(x−α)(x−β)  ⇒α+β=−1  ⇒αβ=4  is this what you mean?
p(x)=x3+3x4=(x1)(x2+Ax+B)=x3+(A1)x2+(BA)xBB=4A1=0A=1BA=41=3=!3p(x)=x3+3x4=(x1)(x2+x+4)=(x1)(xα)(xβ)α+β=1αβ=4isthiswhatyoumean?
Answered by tanmay.chaudhury50@gmail.com last updated on 13/Jul/18
x^3 +3x−3−1  x^3 −1+3(x−1)  (x−1)(x^2 +x+1)+3(x−1)  (x−1)(x^2 +x+4)  one root is 1  another two α and β  α+β=−1   ∝β=4
x3+3x31x31+3(x1)(x1)(x2+x+1)+3(x1)(x1)(x2+x+4)onerootis1anothertwoαandβα+β=1β=4

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