Solve for x
x=-10
x=3
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\left(x-5\right)\left(x+1\right)-\left(x+5\right)\left(x-2\right)=\left(x-5\right)\left(x+5\right)
Variable x cannot be equal to any of the values -5,5 since division by zero is not defined. Multiply both sides of the equation by \left(x-5\right)\left(x+5\right), the least common multiple of x+5,x-5.
x^{2}-4x-5-\left(x+5\right)\left(x-2\right)=\left(x-5\right)\left(x+5\right)
Use the distributive property to multiply x-5 by x+1 and combine like terms.
x^{2}-4x-5-\left(x^{2}+3x-10\right)=\left(x-5\right)\left(x+5\right)
Use the distributive property to multiply x+5 by x-2 and combine like terms.
x^{2}-4x-5-x^{2}-3x+10=\left(x-5\right)\left(x+5\right)
To find the opposite of x^{2}+3x-10, find the opposite of each term.
-4x-5-3x+10=\left(x-5\right)\left(x+5\right)
Combine x^{2} and -x^{2} to get 0.
-7x-5+10=\left(x-5\right)\left(x+5\right)
Combine -4x and -3x to get -7x.
-7x+5=\left(x-5\right)\left(x+5\right)
Add -5 and 10 to get 5.
-7x+5=x^{2}-25
Consider \left(x-5\right)\left(x+5\right). Multiplication can be transformed into difference of squares using the rule: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}. Square 5.
-7x+5-x^{2}=-25
Subtract x^{2} from both sides.
-7x+5-x^{2}+25=0
Add 25 to both sides.
-7x+30-x^{2}=0
Add 5 and 25 to get 30.
-x^{2}-7x+30=0
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=\frac{-\left(-7\right)±\sqrt{\left(-7\right)^{2}-4\left(-1\right)\times 30}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, -7 for b, and 30 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-7\right)±\sqrt{49-4\left(-1\right)\times 30}}{2\left(-1\right)}
Square -7.
x=\frac{-\left(-7\right)±\sqrt{49+4\times 30}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{-\left(-7\right)±\sqrt{49+120}}{2\left(-1\right)}
Multiply 4 times 30.
x=\frac{-\left(-7\right)±\sqrt{169}}{2\left(-1\right)}
Add 49 to 120.
x=\frac{-\left(-7\right)±13}{2\left(-1\right)}
Take the square root of 169.
x=\frac{7±13}{2\left(-1\right)}
The opposite of -7 is 7.
x=\frac{7±13}{-2}
Multiply 2 times -1.
x=\frac{20}{-2}
Now solve the equation x=\frac{7±13}{-2} when ± is plus. Add 7 to 13.
x=-10
Divide 20 by -2.
x=-\frac{6}{-2}
Now solve the equation x=\frac{7±13}{-2} when ± is minus. Subtract 13 from 7.
x=3
Divide -6 by -2.
x=-10 x=3
The equation is now solved.
\left(x-5\right)\left(x+1\right)-\left(x+5\right)\left(x-2\right)=\left(x-5\right)\left(x+5\right)
Variable x cannot be equal to any of the values -5,5 since division by zero is not defined. Multiply both sides of the equation by \left(x-5\right)\left(x+5\right), the least common multiple of x+5,x-5.
x^{2}-4x-5-\left(x+5\right)\left(x-2\right)=\left(x-5\right)\left(x+5\right)
Use the distributive property to multiply x-5 by x+1 and combine like terms.
x^{2}-4x-5-\left(x^{2}+3x-10\right)=\left(x-5\right)\left(x+5\right)
Use the distributive property to multiply x+5 by x-2 and combine like terms.
x^{2}-4x-5-x^{2}-3x+10=\left(x-5\right)\left(x+5\right)
To find the opposite of x^{2}+3x-10, find the opposite of each term.
-4x-5-3x+10=\left(x-5\right)\left(x+5\right)
Combine x^{2} and -x^{2} to get 0.
-7x-5+10=\left(x-5\right)\left(x+5\right)
Combine -4x and -3x to get -7x.
-7x+5=\left(x-5\right)\left(x+5\right)
Add -5 and 10 to get 5.
-7x+5=x^{2}-25
Consider \left(x-5\right)\left(x+5\right). Multiplication can be transformed into difference of squares using the rule: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}. Square 5.
-7x+5-x^{2}=-25
Subtract x^{2} from both sides.
-7x-x^{2}=-25-5
Subtract 5 from both sides.
-7x-x^{2}=-30
Subtract 5 from -25 to get -30.
-x^{2}-7x=-30
Quadratic equations such as this one can be solved by completing the square. In order to complete the square, the equation must first be in the form x^{2}+bx=c.
\frac{-x^{2}-7x}{-1}=-\frac{30}{-1}
Divide both sides by -1.
x^{2}+\left(-\frac{7}{-1}\right)x=-\frac{30}{-1}
Dividing by -1 undoes the multiplication by -1.
x^{2}+7x=-\frac{30}{-1}
Divide -7 by -1.
x^{2}+7x=30
Divide -30 by -1.
x^{2}+7x+\left(\frac{7}{2}\right)^{2}=30+\left(\frac{7}{2}\right)^{2}
Divide 7, the coefficient of the x term, by 2 to get \frac{7}{2}. Then add the square of \frac{7}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+7x+\frac{49}{4}=30+\frac{49}{4}
Square \frac{7}{2} by squaring both the numerator and the denominator of the fraction.
x^{2}+7x+\frac{49}{4}=\frac{169}{4}
Add 30 to \frac{49}{4}.
\left(x+\frac{7}{2}\right)^{2}=\frac{169}{4}
Factor x^{2}+7x+\frac{49}{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{7}{2}\right)^{2}}=\sqrt{\frac{169}{4}}
Take the square root of both sides of the equation.
x+\frac{7}{2}=\frac{13}{2} x+\frac{7}{2}=-\frac{13}{2}
Simplify.
x=3 x=-10
Subtract \frac{7}{2} from both sides of the equation.
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