Question

Tìm x,biết:
a)(5-x).(x-1)=-2x.(x-1)
b)(x+3)²-(x-13).(x+13)=0

Answer 1

a) \(\left(5-x\right)\left(x-1\right)=-2x\left(x-1\right)\)

\(\Rightarrow\left(5-x\right)\left(x-1\right)+2x\left(x-1\right)=0\)

\(\Rightarrow\left(x-1\right)\left(5-x+2x\right)=0\)

\(\Rightarrow\left(x-1\right)\left(x+5\right)=0\)

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

b) \(\left(x+3\right)^2-\left(x-13\right)\left(x+13\right)=0\)

\(\Rightarrow x^2+6x+9-x^2+169=0\)

\(\Rightarrow6x=-178\Rightarrow x=-\dfrac{89}{3}\)