Solve for x
x=-1
x=5
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x^{2}-4x-5=0
Multiply 0 and 714111044445448445 to get 0.
a+b=-4 ab=-5
To solve the equation, factor x^{2}-4x-5 using formula x^{2}+\left(a+b\right)x+ab=\left(x+a\right)\left(x+b\right). To find a and b, set up a system to be solved.
a=-5 b=1
Since ab is negative, a and b have the opposite signs. Since a+b is negative, the negative number has greater absolute value than the positive. The only such pair is the system solution.
\left(x-5\right)\left(x+1\right)
Rewrite factored expression \left(x+a\right)\left(x+b\right) using the obtained values.
x=5 x=-1
To find equation solutions, solve x-5=0 and x+1=0.
x^{2}-4x-5=0
Multiply 0 and 714111044445448445 to get 0.
a+b=-4 ab=1\left(-5\right)=-5
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as x^{2}+ax+bx-5. To find a and b, set up a system to be solved.
a=-5 b=1
Since ab is negative, a and b have the opposite signs. Since a+b is negative, the negative number has greater absolute value than the positive. The only such pair is the system solution.
\left(x^{2}-5x\right)+\left(x-5\right)
Rewrite x^{2}-4x-5 as \left(x^{2}-5x\right)+\left(x-5\right).
x\left(x-5\right)+x-5
Factor out x in x^{2}-5x.
\left(x-5\right)\left(x+1\right)
Factor out common term x-5 by using distributive property.
x=5 x=-1
To find equation solutions, solve x-5=0 and x+1=0.
x^{2}-4x-5=0
Multiply 0 and 714111044445448445 to get 0.
x=\frac{-\left(-4\right)±\sqrt{\left(-4\right)^{2}-4\left(-5\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, -4 for b, and -5 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-4\right)±\sqrt{16-4\left(-5\right)}}{2}
Square -4.
x=\frac{-\left(-4\right)±\sqrt{16+20}}{2}
Multiply -4 times -5.
x=\frac{-\left(-4\right)±\sqrt{36}}{2}
Add 16 to 20.
x=\frac{-\left(-4\right)±6}{2}
Take the square root of 36.
x=\frac{4±6}{2}
The opposite of -4 is 4.
x=\frac{10}{2}
Now solve the equation x=\frac{4±6}{2} when ± is plus. Add 4 to 6.
x=5
Divide 10 by 2.
x=-\frac{2}{2}
Now solve the equation x=\frac{4±6}{2} when ± is minus. Subtract 6 from 4.
x=-1
Divide -2 by 2.
x=5 x=-1
The equation is now solved.
x^{2}-4x-5=0
Multiply 0 and 714111044445448445 to get 0.
x^{2}-4x=5
Add 5 to both sides. Anything plus zero gives itself.
x^{2}-4x+\left(-2\right)^{2}=5+\left(-2\right)^{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=5+4
Square -2.
x^{2}-4x+4=9
Add 5 to 4.
\left(x-2\right)^{2}=9
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{9}
Take the square root of both sides of the equation.
x-2=3 x-2=-3
Simplify.
x=5 x=-1
Add 2 to both sides of the equation.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}