Câu hỏi của kien nguyen

Question

Bai 1 :cho A(x)=2x^2-8x

tim nghiem A(x)

b,tim B(x) biet B(x)=A(x)-3x+2x^2

c,tim ngiem B(x)

Bai2

Cho ham so y=f(x)=x+1

cac diem sau diem nao thuoc do thi ham so :A(0;1).B(1/2;-1). C(-1/2;0)

Trương Tú Nhi · Accepted Answer

a,$2x^2-8x=0$

$2x\left(x-4\right)=0$

$\Leftrightarrow\left\{{}\begin{matrix}2x=0\x-4=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\x=4\end{matrix}\right.$

b,$B\left(x\right)=\left(2x^2-8x\right)-\left(3x+2x^2\right)$

$=2x^2-8x-3x-2x^2$

=$-11x$

c,$-11x=0$

$\Rightarrow x=0$Câu trả lời: a,$2x^2-8x=0$

$2x\left(x-4\right)=0$

$\Leftrightarrow\left\{{}\begin{matrix}2x=0\x-4=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\x=4\end{matrix}\right.$

b,$B\left(x\right)=\left(2x^2-8x\right)-\left(3x+2x^2\right)$

$=2x^2-8x-3x-2x^2$

=$-11x$

c,$-11x=0$

$\Rightarrow x=0$

Mashiro Shiina · Answer

$A\left(x\right)=2x^2-8x$

$\Rightarrow2x^2-8x=0$

$\Rightarrow x\left(2x-8\right)=0$

$\Rightarrow\left[{}\begin{matrix}x=0\2x=8\Rightarrow x=4\end{matrix}\right.$

$B\left(x\right)=-3x+2x^2$

$B\left(x\right)=2x^2-3x$

$2x^2-3x=0$

$\Rightarrow x\left(2x-3\right)=0$

$\Rightarrow\left[{}\begin{matrix}x=0\2x=3\Rightarrow x=\dfrac{3}{2}\end{matrix}\right.$Câu trả lời: $A\left(x\right)=2x^2-8x$