Solve for x
x=4
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\left(x-5\right)\left(x-4\right)+\left(x+4\right)\left(x+5\right)=2x\left(x+5\right)
Variable x cannot be equal to any of the values -4,5 since division by zero is not defined. Multiply both sides of the equation by \left(x-5\right)\left(x+4\right), the least common multiple of x+4,x-5,x^{2}-x-20.
x^{2}-9x+20+\left(x+4\right)\left(x+5\right)=2x\left(x+5\right)
Use the distributive property to multiply x-5 by x-4 and combine like terms.
x^{2}-9x+20+x^{2}+9x+20=2x\left(x+5\right)
Use the distributive property to multiply x+4 by x+5 and combine like terms.
2x^{2}-9x+20+9x+20=2x\left(x+5\right)
Combine x^{2} and x^{2} to get 2x^{2}.
2x^{2}+20+20=2x\left(x+5\right)
Combine -9x and 9x to get 0.
2x^{2}+40=2x\left(x+5\right)
Add 20 and 20 to get 40.
2x^{2}+40=2x^{2}+10x
Use the distributive property to multiply 2x by x+5.
2x^{2}+40-2x^{2}=10x
Subtract 2x^{2} from both sides.
40=10x
Combine 2x^{2} and -2x^{2} to get 0.
10x=40
Swap sides so that all variable terms are on the left hand side.
x=\frac{40}{10}
Divide both sides by 10.
x=4
Divide 40 by 10 to get 4.
Examples
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Simultaneous equation
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Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
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Limits
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