Question

计算(2x+3)^2(2x-3)^2

计算(x+y-4)(x+y+4)，计算：(a-1)(a+1)(a^2-1）

Answer 1

1. （4x^2-9)^2=16x^4-72x^2+81
2. =(x+y)^2-16=x^2+2xy+Y^2-16
3. =(a^2-1)^2=a^4-2a^2+1

Answer 2

(2x+3)^2(2x-3)^2=(4x^2-9)^2=16x^4-72x^2+81

(x+y-4)(x+y+4)=(x+y)^2-16=x^2+2xy+y^2-16

(a-1)(a+1)(a^2-1)=(a^2-1)^2 =a^4-2a^2+1