Question

1.Rút gọn :

(x-1)^2-(x+4)(x-4)

2. Tìm x:

3(2x-4)+15=-11

x(x+2)-3x-6=0

Answer 1

Bài 1:

\(\left(x-1\right)^2-\left(x+4\right)\left(x-4\right)=x^2-2x+1-x^2+16=17-2x\)

Bài 2:

a) \(3\left(2x-4\right)+15=-11\)

\(\Leftrightarrow6x-12+15=-11\)

\(\Leftrightarrow6x=-14\)

\(\Leftrightarrow x=-\frac{7}{3}\)

b) \(x\left(x+2\right)-3x-6=0\)

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

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

\(\Leftrightarrow\left[\begin{array}{nghiempt}x+2=0\\x-3=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=-2\\x=3\end{array}\right.\)