Đáp án:
Bài 1:
$a) x=10\\
2) x=-16\\
3)
x=45\\
4)
x=-3\\
5)
{\left[\begin{aligned}x=20\\x=-14\end{aligned}\right.}\\
6)
{\left[\begin{aligned}x=8\\x=-2\end{aligned}\right.}\\
7)
{\left[\begin{aligned}x=\dfrac{15}{2}\\ x=3\end{aligned}\right.}\\
8)
{\left[\begin{aligned}x=0\\ x=2\end{aligned}\right.}\\
9)
{\left[\begin{aligned}x=6\\ x=-4\end{aligned}\right.}\\
10)
x=6$
Giải thích các bước giải:
Bài 1:
$a) 3x-17=x+3\Leftrightarrow 3x-x=3+17\Leftrightarrow 2x=20\Leftrightarrow x=10\\
2) 2x-15=-47\Leftrightarrow 2x=-47+15=-32\Leftrightarrow x=-16\\
3)
25-(x-5)=-415-(15-415)\Leftrightarrow 25-x+5=-415-15+415\\
\Leftrightarrow -x=-15-30=-45\Leftrightarrow x=45\\
4)
(-5)^2-(5x-3)=43\Leftrightarrow 25-5x+3=43\\
\Leftrightarrow 5x=28-43=-15\Leftrightarrow x=-3\\
5)
\left | x-3 \right |-12=\left | -5 \right |\\
\Leftrightarrow \left | x-3 \right |=5+12=17\\
\Leftrightarrow {\left[\begin{aligned}x-3=17\\x-3=-17\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=20\\x=-14\end{aligned}\right.}\\
6)
3\left | x-3 \right |-1=(-2)(-7)\\
\Leftrightarrow 3\left | x-3 \right |=14+1=15\\
\Leftrightarrow \left | x-3 \right |=5\\
\Leftrightarrow {\left[\begin{aligned}x-3=5\\x-3=-5\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=8\\x=-2\end{aligned}\right.}\\
7)
(2x-15)(3-x)=0\\
\Leftrightarrow {\left[\begin{aligned}2x-15=0\\ 3-x=0\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}2x=15\\ x=3\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=\dfrac{15}{2}\\ x=3\end{aligned}\right.}\\
8)
x(x-5)+3x=0\\
\Leftrightarrow x(x-5+3)=0\\
\Leftrightarrow x(x-2)=0\\
\Leftrightarrow {\left[\begin{aligned}x=0\\ x-2=0\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=0\\ x=2\end{aligned}\right.}\\
9)
(x-1)^2-3=|-22|\\
\Leftrightarrow (x-1)^2=22+3=25\\
\Leftrightarrow x-1=\pm 5\\
\Leftrightarrow {\left[\begin{aligned}x-1=5\\ x-1=-5\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=6\\ x=-4\end{aligned}\right.}\\
10)
12+(3-x)^3=-15\\
\Leftrightarrow (3-x)^3=-15-12=-27\\
\Leftrightarrow (3-x)^3=(-3)^3\\
\Leftrightarrow 3-x=-3\\
\Leftrightarrow x=3+3=6$
