(1)x(1-x)²=64%x(2)200(1+x)²=1400(3)x(x-1)=2970

问题描述:

(1)x(1-x)²=64%x
(2)200(1+x)²=1400
(3)x(x-1)=2970

(1) 1-x=0.8 x=0.2
(2) x=根号7减1
(3) x=55

(1)x(1-x)²=64%x
x(1-x-0.64)=0
x(0.36-x) =0 x=0 或x=0.36
(2)200(1+x)²=1400
(1+x)^2=7 x=-1±√7
(3)x(x-1)=2970
x=55或x=-54

1,X=0.2
2.X={根号7}-1
3.X=56

(1)x=0或者x=0.2或x=1.2
(2)x=-1+根号7或x=-1-根号7
(3)x=55或x=-54

(1) a,当x=0时左边等于右边;b,当x不等于0时:(1-x)²=64%得,x=20% 或者x=120%
(2) 等式化简为 (1+x)²=7 得:x=正负根号7 -1
(3) x²-x=2970 即 x²-x+0.25=2970.25 即 (x-0.5)²=2970.25 解得 x=54.5+0.5=55或者x=-54.5+0.5=-54