如何做 1.3x2 -5x+5x2 -3x 2.5n + 11 = 7n - 9 3.4(3x - 5) = - 2(- x + 8) - 6x
问题描述：
如何做 1.3x2 -5x+5x2 -3x 2.5n + 11 = 7n - 9 3.4(3x - 5) = - 2(- x + 8) - 6x
答
3x^2-5x+5x^2-3x
=(3+5)x^2+(-5-3)x
=8x^2-8x
5n+11=7n-9
-2n=-20
n=10
4(3x-5)=-2(-x+8)-6x
12x-20=2x-16-6x
12x-20=-4x-16
16x=4
x=1/4