Question

Cho a+b=1 và ab=-20.Tính

a)A=b(a-1)+a(b-1)

b)B=a²+b²

c)C=(a-b)²

d)D=a⁴+b⁴

^{GIÚP MÌNH MÌNH CẦN GẤP!!!}

Answer 1

\(A=ab-a+ab-a=2ab-\left(a+b\right)=2.\left(-20\right)-1=-41\)

\(B=a^2+b^2=\left(a+b\right)^2-2ab=1^2-2.\left(-20\right)=41\)

\(C=\left(a-b\right)^2=\left(a+b\right)^2-4ab=1^2-4\left(-20\right)=81\)

\(D=a^4+b^4=\left(a^2+b^2\right)^2-2\left(ab\right)^2=41^2-2.\left(-20\right)^2=881\)