Question

Rút gọn biểu thức

a) (y-2)(y+2)(y²+4) - (y+3)(y-3)(y²+9)

b) 2(x²-xy+y²)(x-y)(x²+y²+y²)(x+y) - 2(x⁶-y⁶)

Answer 1

a) \(\left(y-2\right)\cdot\left(y+2\right)\cdot\left(y^2+4\right)-\left(y+3\right)\cdot\left(y-3\right)\cdot\left(y^2+9\right)=\left(y^2-2^2\right)\cdot\left(y^2+2^2\right)-\left(y^2-3^2\right)\cdot\left(y^2+3^2\right)=y^4-2^4-y^4+3^4=3^4-2^4=65\)

Answer 2

a: \(=\left(y^2-4\right)\left(y^2+4\right)-\left(y^2-9\right)\left(y^2+9\right)\)

\(=y^4-16-y^4+81=65\)

c: \(=2\left(x^6-y^6\right)-2\cdot\left(x^6-y^6\right)=0\)