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x^{2}+4x+5-5=0
Subtract 5 from both sides.
x^{2}+4x=0
Subtract 5 from 5 to get 0.
x\left(x+4\right)=0
Factor out x.
x=0 x=-4
To find equation solutions, solve x=0 and x+4=0.
x^{2}+4x+5=5
All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. The quadratic formula gives two solutions, one when ± is addition and one when it is subtraction.
x^{2}+4x+5-5=5-5
Subtract 5 from both sides of the equation.
x^{2}+4x+5-5=0
Subtracting 5 from itself leaves 0.
x^{2}+4x=0
Subtract 5 from 5.
x=\frac{-4±\sqrt{4^{2}}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 4 for b, and 0 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-4±4}{2}
Take the square root of 4^{2}.
x=\frac{0}{2}
Now solve the equation x=\frac{-4±4}{2} when ± is plus. Add -4 to 4.
x=0
Divide 0 by 2.
x=-\frac{8}{2}
Now solve the equation x=\frac{-4±4}{2} when ± is minus. Subtract 4 from -4.
x=-4
Divide -8 by 2.
x=0 x=-4
The equation is now solved.
x^{2}+4x+5-5=0
Subtract 5 from both sides.
x^{2}+4x=0
Subtract 5 from 5 to get 0.
x^{2}+4x+2^{2}=2^{2}
Divide 4, the coefficient of the x term, by 2 to get 2. Then add the square of 2 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+4x+4=4
Square 2.
\left(x+2\right)^{2}=4
Factor x^{2}+4x+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+2\right)^{2}}=\sqrt{4}
Take the square root of both sides of the equation.
x+2=2 x+2=-2
Simplify.
x=0 x=-4
Subtract 2 from both sides of the equation.