Đáp án:
$f(-1)=\dfrac{-11}{2}\\
f(\dfrac{-3}{10})=2\\
a)
x=\dfrac{-11}{2}\\
b) {\left[\begin{aligned}x=1\\x=2\end{aligned}\right.}\\$
Giải thích các bước giải:
$f(-1)=5.(-1)-\dfrac{1}{2}=\dfrac{(-5).2}{2}-\dfrac{1}{2}=\dfrac{-11}{2}\\
f(\dfrac{-3}{10})=5.\dfrac{-3}{10}-\dfrac{1}{2}=\dfrac{-15}{10}-\dfrac{5}{10}=\dfrac{-20}{10}=2\\
a)
(x-4)-3(x+1)-4=0\\
\Leftrightarrow x-4-3x-3-4=0\\
\Leftrightarrow -2x-11=0\\
\Leftrightarrow -2x=11\\
\Leftrightarrow x=\dfrac{-11}{2}\\
b) x^2-3x+2=0\\
\Leftrightarrow x^2-x-2x+2=0\\
\Leftrightarrow x(x-1)-2(x-1)=0\\
\Leftrightarrow (x-1)(x-2)=0\\
\Leftrightarrow {\left[\begin{aligned}x-1=0\\x-2=0\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=1\\x=2\end{aligned}\right.}\\$