Question

 

Tìm x, biết:

a, (x+1).(x+2)-x^2-x=0

b, 2x^2+5x-3=0

Tìm GTNN của biểu thức

P= (4x^2+8x).(x^2+2x+2)-8

 

Answer 1

Tìm x

a) \(\left(x+1\right)\left(x+2\right)-x^2-x=0\)

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

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

\(\Leftrightarrow2\left(x+1\right)=0\)

\(\Leftrightarrow x+1=0\Leftrightarrow x=-1\)

b) \(2x^2+5x-3=0\)

\(\Leftrightarrow2x^2+6x-x-3=0\)

\(\Leftrightarrow2x\left(x+3\right)-\left(x+3\right)=0\)

\(\Leftrightarrow\left(2x-1\right)\left(x+3\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{1}{2}\\x=-3\end{array}\right.\)