Question

Tìm x bít \(x^3+3x^2+3x+1=-1\)

Answer 1

Áp dụng hằng đẳng thức số 4 , ta có :

x³ + 3x² + 3x + 1 = -1

=> (x + 1)³ = -1

<=> x + 1 = -1

<=> x = -2

Answer 2

\(x^3+3x^2+3x+1=-1\)

\(\Rightarrow\left(x+1\right)^3=-1\)

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

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

\(\Rightarrow x=-2\)

Vậy \(x=-2\)

Answer 3

x=-2

Answer 4

\(x^3+3x^2+3x+1=-1\)

\(\Rightarrow x^3+x^2+2x^2+2x+x+1=-1\)

\(\Rightarrow\left(x^3+x^2\right)+\left(2x^2+2x\right)+\left(x+1\right)=-1\)

\(\Rightarrow x^2.\left(x+1\right)+2x.\left(x+1\right)+\left(x+1\right)=-1\)

\(\Rightarrow\left(x+1\right).\left(x^2+2x+1\right)=-1\)

\(\Rightarrow\left(x+1\right).\left(x^2+x+x+1\right)=-1\)

\(\Rightarrow\left(x+1\right)^3=-1\)

\(\Rightarrow x+1=-1\Rightarrow x=-2\)

Vậy \(x=-2\)

Chúc bạn học tốt!!!