急急急!!快答!!

恆等式
因 應用式a (a+b)²=a²+2ab+b²
應用式b (a-b)²=a²-2ab+b²
應用式c (a+b)(a-b)=a²-b²

1.18a² +48ab+32b² ----------------------------ans:2(3a+4b) ←呢到你個ans打錯左
=2(9a²+24ab+16b²)
=2(3a+4b)²

2.20x² +60xy+45y² ----------------------------ans:5(2x+3y)←呢到你個ans打錯左
=5(4x²+14xy+9y²)
=5(2x+3y)²

3.(x+y)² -49----------------------------ans:(x+y-7)(x+y+7)
=(x+y)² -(7)²
=(x+y+y)(x+y-7)

4.(2x-y)² -x² ----------------------------ans:(x-y)(3x-y)
=(2x-y) -(x)²
=(2x-y-x)(2x-y+x)
=(x+y)(3x+y)

5.(a-b)² -(a+b)² ----------------------------ans:-4ab
=[(a-b)-(a+b)][(a-b)+(a+b)]
=(-2b)(2a)
=-4ab

6.(a-2b)² -(a+b)² ----------------------------ans:-3b(2a-b)
=[(a-2b)+(a+b)][(a-2b)-(a+b)]
=(2a-b)(-3b)
=-6ab+3b²
=-3b(2a-b)