Question

Tìm x biết

a) x²-2x=-1

b) x³+3x²=-3x-1

Answer 1

a) x = 1

b) x = -1

Answer 2

a) x²-2x=-1

<=> x²-2x+1=0

<=> (x - 1)² = 0
=> x = 1

 

Answer 3

a: Ta có: \(x^2-2x=-1\)

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

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

\(\Leftrightarrow x-1=0\)

hay x=1

b: Ta có: \(x^3+3x^2=-3x-1\)

\(\Leftrightarrow x^3+3x^2+3x+1=0\)

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

\(\Leftrightarrow x+1=0\)

hay x=-1