1.解方程,(x+2)^2-7=0,用a+根号b的形式表达.2.2(3^w)=7+9^w/2-2(3^w+1),求W3.化最简形式：2/1-2x+3(x-1)/2x^2-5x+2+1/x-2.就这三题,

Question

1.解方程,(x+2)^2-7=0,用a+根号b的形式表达.
2.2(3^w)=7+9^w/2-2(3^w+1),求W
3.化最简形式：2/1-2x + 3(x-1)/2x^2-5x+2 + 1/x-2 .
就这三题,

Answer 1

1.x+2 = ±√7,x = -2 +√7 或 x= -2-√7
2.令 u = 3^w,即:2u = 7 + (1/2)u² - 2(u+1)
u² - 8u +10 = 0 => u = 4 +√6 或 u = 4 -√6
=> w = Log[3,4 +√6] 或 w = Log[3,4 -√6]
3.原式 = [ -2(x-2) + 3(x-1) + (2x-1) ] / [(2x-1)(x-2)]
= 3x / [(2x-1)(x-2)]