因式分解
(2x+y)的平方-(x+2y)的平方
=(2x+y+x+2y)(2x+y-x-2y)
=(3x+3y)(x-y)
=3(x+y)(x-y)
5(x-2)的平方+a(2-x)
=5(x-2)-a(x-2)
=(x-2)(5-a)
(2a-3b)(7x+y)+(x-5y)(3b-2a)
=(2a-3b)(7x+y)-(x-5y)(2a-3b)
=(2a-3b)(7x+y-x+5y)
=(2a-3b)(6x+6y)
=6(2a-3b)(x+y)
23.1*24-46.2*7
=23.1*24-23.1*14
=23.1(24-14)
=231