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x^{2}+2x+1=1-3x
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(x+1\right)^{2}.
x^{2}+2x+1-1=-3x
Subtract 1 from both sides.
x^{2}+2x=-3x
Subtract 1 from 1 to get 0.
x^{2}+2x+3x=0
Add 3x to both sides.
x^{2}+5x=0
Combine 2x and 3x to get 5x.
x\left(x+5\right)=0
Factor out x.
x=0 x=-5
To find equation solutions, solve x=0 and x+5=0.
x^{2}+2x+1=1-3x
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(x+1\right)^{2}.
x^{2}+2x+1-1=-3x
Subtract 1 from both sides.
x^{2}+2x=-3x
Subtract 1 from 1 to get 0.
x^{2}+2x+3x=0
Add 3x to both sides.
x^{2}+5x=0
Combine 2x and 3x to get 5x.
x=\frac{-5±\sqrt{5^{2}}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 5 for b, and 0 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-5±5}{2}
Take the square root of 5^{2}.
x=\frac{0}{2}
Now solve the equation x=\frac{-5±5}{2} when ± is plus. Add -5 to 5.
x=0
Divide 0 by 2.
x=-\frac{10}{2}
Now solve the equation x=\frac{-5±5}{2} when ± is minus. Subtract 5 from -5.
x=-5
Divide -10 by 2.
x=0 x=-5
The equation is now solved.
x^{2}+2x+1=1-3x
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(x+1\right)^{2}.
x^{2}+2x+1-1=-3x
Subtract 1 from both sides.
x^{2}+2x=-3x
Subtract 1 from 1 to get 0.
x^{2}+2x+3x=0
Add 3x to both sides.
x^{2}+5x=0
Combine 2x and 3x to get 5x.
x^{2}+5x+\left(\frac{5}{2}\right)^{2}=\left(\frac{5}{2}\right)^{2}
Divide 5, the coefficient of the x term, by 2 to get \frac{5}{2}. Then add the square of \frac{5}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+5x+\frac{25}{4}=\frac{25}{4}
Square \frac{5}{2} by squaring both the numerator and the denominator of the fraction.
\left(x+\frac{5}{2}\right)^{2}=\frac{25}{4}
Factor x^{2}+5x+\frac{25}{4}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.
\sqrt{\left(x+\frac{5}{2}\right)^{2}}=\sqrt{\frac{25}{4}}
Take the square root of both sides of the equation.
x+\frac{5}{2}=\frac{5}{2} x+\frac{5}{2}=-\frac{5}{2}
Simplify.
x=0 x=-5
Subtract \frac{5}{2} from both sides of the equation.