Question

解方程(1)(x+1)(x-6)=8 (2)25(x-2)^2=16(x+4)^2？

Answer 1

1
(x+1)(x-6)=8
x^2-6x+x-6-8=0
x^2-5x-14=0
(x-7)(x+2)=0
解得x=7,-2
2
25(x-2)^2=16(x+4)^2
化简得3X^2-76X-52=0
(X-26)(3X+2)=0
解得X=26,-2/3
还可以这样做
5^2(x-2)^2=4^2(x+4)^2
5*(X-2)=正负4*(X+4)
答案一样的.,8,(1)X^2-5X-6=8
X^2-5X-14=0
(X-7)(X+2)=0
=>X=7 OR X=-2
(2)25(X^2-4X+4)=16(X^2+8X+16)
25X^2-100X+100=16X^2+128X+256
9X^2-228X-156=0
3X^2-76X-52=0
(3X+2)(X-26)=0
=>X=-2/3 OR X=26,0,