Question

Answer 1

a: \(A=\left(x+y\right)^2-2\left(x+y\right)\left(x-y\right)+\left(y-x\right)^2\)

\(=\left(x+y\right)^2-2\left(x+y\right)\left(x-y\right)+\left(x-y\right)^2\)

\(=\left(x+y-x+y\right)^2=\left(2y\right)^2=4y^2\)

Khi y=-3 thì \(A=4\cdot\left(-3\right)^2=4\cdot9=36\)

b: \(2x^4-10x^3-x^2+15x-a\)

\(=2x^4-3x^2-10x^3+15x+2x^2-3+3-a\)

\(=\left(2x^2-3\right)\left(x^2-5x+1\right)+3-a\)

=>Để \(2x^4-10x^3-x^2+15x-a\) chia hết cho \(2x^2-3\) thì 3-a=0

=>a=3