Question

Tìm x biết :

7(x-1)+2x(1-x)=0

Answer 1

7 ( x - 1 ) + 2x ( 1 - x ) = 0

7 . x - 7 x 1 + 2x . 1 - 2x . x = 0

7x - 7x + 2x - 2x\(^2\) = 0

2x - 2\(^2\)= 0

2x          = 0 + 2\(^2\)

2x         = 4

 x          = 4 : 2 

 x          = 2

Answer 2

7(x-1)+2x(1-x)=0

7(x-1)-2x(x-1)=0

(x-1).(7-2x)=0

\(\Rightarrow\)\(\orbr{\begin{cases}x-1=0\\7-2x=0\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x=1\\x=\frac{7}{2}\end{cases}}\)

Answer 3

7(x-1)+2x(1-x)=0

=>(7-2x)(x-1)=0

=>7-2x=0 hoặc x-1=0

+)Nếu 7-2x=0

=>2x=7

=>x=\(\frac{7}{2}\)

+)Nếu x-1=0

=>x=1