Question

Giải phương Trình

a) x³ +1= x(x+1)

b) x³ + x² + x+1=0

c) x²-3x+2=0

d) 4x² -12x+5=0

Answer 1

a/

x³ +1=x(x+1) \(\Leftrightarrow\) (x+1)(x² -x+1)=x(x+1)

\(\Leftrightarrow\) (x+1)(x² -x+1)- x(x+1)=0

\(\Leftrightarrow\)(x+1)(x² -x+1 -x)=0

\(\Leftrightarrow\) (x+1)(x² -2x+1)=0 \(\Leftrightarrow\)(x+1)(x -1)²=0

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

vậy x=-1, x=1

Answer 2

b/

x³+x²+x+1=0 \(\Leftrightarrow\)(x³+x²)+(x+1)=0

\(\Leftrightarrow\) x²(x+1)+(x+1)=0

\(\Leftrightarrow\) (x+1)(x²+1)=0

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

vậy x=-1

Answer 3

c/

x²-3x+2=0 \(\Leftrightarrow\) x² -2x-x+2=0

\(\Leftrightarrow\) (x² -2x)-(x-2)=0 \(\Leftrightarrow x\left(x-2\right)-\left(x-2\right)=0\)

\(\Leftrightarrow\) (x-2)(x-1)=0

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

vậy x=2,x=1

Answer 4

d/

4x²-12x+5=0 \(\Leftrightarrow\) 4x²-2x-10x+5=0

\(\Leftrightarrow\)(4x²-2x)-(10x-5)=0 \(\Leftrightarrow\) 2x(2x-1)-5(2x-1)=0

\(\Leftrightarrow\) (2x-1)(2x-5)=0

\(\Leftrightarrow\)\(\left[\begin{matrix}2x-1=0\\2x-5=0\end{matrix}\right.\)\(\Leftrightarrow\)\(\left[\begin{matrix}x=\frac{1}{2}\\x=\frac{5}{2}\end{matrix}\right.\)

vậy x=\(\frac{1}{2}\),x=\(\frac{5}{2}\)

Answer 5

câu A x=1 hoặc -1

Answer 6

câu B x=-1

cau C x=1 hoặc =2

cauD x= 5/2 hoặc x=1/2