-4x二次方+25（x+3y)(2x-y)2(x+5)(x-4)-3(x-6)(x+1)13.25二次方-6.25二次方(简算）分解因式：4x（a-b)-8y(b-a)

Question

-4x二次方+25
（x+3y)(2x-y)
2(x+5)(x-4)-3(x-6)(x+1)
13.25二次方-6.25二次方(简算）
分解因式：
4x（a-b)-8y(b-a)

Answer 1

-4x^2+25
=25-4x^2
=(5-2x)(5+2x)
(x+3y)(2x-y)
=2x^2-xy+6xy-3y^2
=2x^2+5xy-3y^2
2(x+5)(x-4)-3(x-6)(x+1)
=2(x^2+x-20)-3(x^2-5x-6)
=2x^2+2x-40-3x^2+15x+18
=2x^2-3x^2+2x+15x-40+18
=-x^2+17x-22
13.25^2-6.25^2
=(13.25+6.25)(13.25-6.25)
=19.5*7
=136.5
4x（a-b)-8y(b-a)
=4x(a-b)+8y(a-b)
=4(a-b)(x+2y)