mk đang cần gấp ạ.
giải các phương trình sau:
a, 3(x-2)= 7(10-4x)
b, 2x^3 + 5x^2 + 3x=0
c, (x+3)(2x-1)= 4(x+3)
d, x(x-2) -3x+6=0
mk đang cần gấp ạ.
giải các phương trình sau:
a, 3(x-2)= 7(10-4x)
b, 2x^3 + 5x^2 + 3x=0
c, (x+3)(2x-1)= 4(x+3)
d, x(x-2) -3x+6=0
Đáp án:
$a) x=\frac{76}{31}\\
b) {\left[\begin{aligned}x=0\\x=-1\\ x=\frac{-3}{2}\end{aligned}\right.}\\
c) {\left[\begin{aligned}x=\frac{5}{2}\\x=-3\end{aligned}\right.}\\
d) {\left[\begin{aligned}x=3\\x=2\end{aligned}\right.}$
Giải thích các bước giải:
$a) 3(x-2)=7(10-4x)\\
\Leftrightarrow 3x-6=70-28x\\
\Leftrightarrow 3x+28x=70+6\\
\Leftrightarrow 31x=76\\
\Leftrightarrow x=\frac{76}{31}\\
b) 2x^3+5x^2+3x=0\\
\Leftrightarrow x(2x^2+5x+3)=0\\
\Leftrightarrow x(2x^2+3x+2x+3)=0\\
\Leftrightarrow x[x(2x+3)+(2x+3)]=0\\
\Leftrightarrow x[(x+1)(2x+3)]=0\\
\Leftrightarrow {\left[\begin{aligned}x=0\\x+1=0\\ 2x+3=0 \end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=0\\x=-1\\ x=\frac{-3}{2}\end{aligned}\right.}\\
c) (x+3)(2x-1)=4(x+3)\\
\Leftrightarrow 2x^2-x+6x-3=4x+12\\
\Leftrightarrow 2x^2+5x-4x-3-12=0\\
\Leftrightarrow 2x^2+x-15=0\\
\Leftrightarrow 2x^2+6x-5x-15=0\\
\Leftrightarrow 2x(x+3)-5(x+3)=0\\
\Leftrightarrow (2x-5)(x+3)=0\\
\Leftrightarrow {\left[\begin{aligned}2x-5=0\\x+3=0\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=\frac{5}{2}\\x=-3\end{aligned}\right.}\\
d) x(x-2)-3x+6=0\\
\Leftrightarrow x^2-2x-3x+6=0\\
\Leftrightarrow x^2-5x+6=0\\
\Leftrightarrow x^2-2x-3x+6=0\\
\Leftrightarrow x(x-2)-3(x-2)=0\\
\Leftrightarrow (x-3)(x-2)=0\\
\Leftrightarrow {\left[\begin{aligned}x-3=0\\x-2=0\end{aligned}\right.}\\
\Leftrightarrow {\left[\begin{aligned}x=3\\x=2\end{aligned}\right.}$