Question

[KHỞI MY LOVE YOU FOREVER]

giải phương trình:

a. x(x-3)-x²+2=0

b.x²-2x+1=0

c.x(x-1)-(x+3)-(x+4)=5x

d.10x+3/8-7-8x/12

e.x²+2x=15

f.x⁴-5x³+4x²=0

Tìm x biết: nếu m=2 thì mx²+mx-2x²+3=0

Answer 1

[Phạm Khánh Linh]

a, \(x\left(x-3\right)-x^2+2=0\)

\(\Leftrightarrow x^2-3x-x^2+2=0\\ \Leftrightarrow-3x+2=0\)

\(\Leftrightarrow-3x=-2\\ \Rightarrow x=\frac{2}{3}\)

b, \(x^2-2x+1=0\\ \Leftrightarrow\left(x-1\right)^2=0^2\)

\(\Leftrightarrow x-1=0\\ \Leftrightarrow x=1\)

c, x(x-1)-(x+3)(x+4)=5x

\(\Leftrightarrow x^2-x-x^2-4x-3x-12=5x\)

\(\Leftrightarrow x^2-x-x^2-4x-3x-5x=12\\ \Leftrightarrow-13x=12\\ \Rightarrow x=\frac{-12}{13}\)

d, ko có vế phải ạ

e, \(x^2+2x=15\)

\(\Leftrightarrow\left(x^2+2x+1\right)-16=0\\ \Leftrightarrow\left(x+1\right)^2-4^2=0\)

\(\Leftrightarrow\left(x+1-4\right)\left(x+1+4\right)=0\\ \Leftrightarrow\left(x-3\right)\left(x+5\right)=0\)

\(\left[{}\begin{matrix}x-3=0\\x+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-5\end{matrix}\right.\)

f, \(x^4-5x^3+4x^2=0\)

\(\Leftrightarrow x^4-x^3-4x^3+4x^2=0\\ \Leftrightarrow x^3\left(x-1\right)-4x^2\left(x-1\right)=0\\ \Leftrightarrow\left(x-1\right)\left(x^3-4x^2\right)=0\)

\(\Leftrightarrow\left(x-1\right).x^2\left(x-4\right)=0\)

\(\left[{}\begin{matrix}x^2=0\\x-1=0\\x-4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\\x=4\end{matrix}\right.\)

Answer 2

[KHỞI MY LOVE YOU FOREVER]

chỗ câu c x+3.x+4 nha mn