Question

Tìm x biết

a,x²- 4x +4=9

b,(x-1) . (x+1)= x(x-3)
c, x²-2xy +y²-2y +1=0

Answer 1

`a, <=> (x-2)^2 = 9`

`->` \(\left[{}\begin{matrix}x-2=3\\x-2=-3\end{matrix}\right.\)

`->` \(\left[{}\begin{matrix}x=5\\x=-1\end{matrix}\right.\)

`b, x^2 -1 = x^2 - 3x`

`-> 3x = 1`

`-> x = 1/3`

`c, (x+y)^2 + (y-1)^2 - y^2 = 0`

`-> y =0, x = 1`.

Answer 2

a: =>(x-2)²=9

=>x-2=3 hoặc x-2=-3

=>x=-1 hoặc x=5

b: =>x²-3x=x²-1

=>-3x=-1

hay x=1/3