(2a+3)(2a+5)(2a-3)(2a-5)2.先化简,再求值(x+3)(x-3)-x(x-2),其中x=4

问题描述:

(2a+3)(2a+5)(2a-3)(2a-5)
2.先化简,再求值(x+3)(x-3)-x(x-2),其中x=4

=(2a+3)(2a-3)(2a+5)(2a-5)
=(4a^2-9)(4a^2-25)
=16a^4-136a^2+225
(2)原式=x^2-9-x^2+2x
=2x-9
代入得原式=-1

(2a+3)(2a+5)(2a-3)(2a-5)
=(2a+3)(2a-3)(2a+5)(2a-5)
=(4a²-9)(4a²-25)
=16a⁴-136a² +225

(2a+3)(2a+5)(2a-3)(2a-5)=(2a+3)(2a-3)(2a+5)(2a-5)=[(2a)²—3²﹚][(2a)²-5²]=(4a²-9)(4a²-25)=16a的四次方—136a²+225 2.先化简,再求值(x+3)(x-3)-x(x-2),其中x=...