Solve for x
x = \frac{\sqrt{21} + 4}{5} \approx 1.716515139
x=\frac{4-\sqrt{21}}{5}\approx -0.116515139
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Quadratic Equation
5 problems similar to:
1 - \frac { x - 3 } { 2 x - 2 } = \frac { 3 x } { x + 1 }
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2\left(x-1\right)\left(x+1\right)-\left(x+1\right)\left(x-3\right)=\left(2x-2\right)\times 3x
Variable x cannot be equal to any of the values -1,1 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-1\right)\left(x+1\right), the least common multiple of 2x-2,x+1.
\left(2x-2\right)\left(x+1\right)-\left(x+1\right)\left(x-3\right)=\left(2x-2\right)\times 3x
Use the distributive property to multiply 2 by x-1.
2x^{2}-2-\left(x+1\right)\left(x-3\right)=\left(2x-2\right)\times 3x
Use the distributive property to multiply 2x-2 by x+1 and combine like terms.
2x^{2}-2-\left(x^{2}-2x-3\right)=\left(2x-2\right)\times 3x
Use the distributive property to multiply x+1 by x-3 and combine like terms.
2x^{2}-2-x^{2}+2x+3=\left(2x-2\right)\times 3x
To find the opposite of x^{2}-2x-3, find the opposite of each term.
x^{2}-2+2x+3=\left(2x-2\right)\times 3x
Combine 2x^{2} and -x^{2} to get x^{2}.
x^{2}+1+2x=\left(2x-2\right)\times 3x
Add -2 and 3 to get 1.
x^{2}+1+2x=\left(6x-6\right)x
Use the distributive property to multiply 2x-2 by 3.
x^{2}+1+2x=6x^{2}-6x
Use the distributive property to multiply 6x-6 by x.
x^{2}+1+2x-6x^{2}=-6x
Subtract 6x^{2} from both sides.
-5x^{2}+1+2x=-6x
Combine x^{2} and -6x^{2} to get -5x^{2}.
-5x^{2}+1+2x+6x=0
Add 6x to both sides.
-5x^{2}+1+8x=0
Combine 2x and 6x to get 8x.
-5x^{2}+8x+1=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{-8±\sqrt{8^{2}-4\left(-5\right)}}{2\left(-5\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -5 for a, 8 for b, and 1 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-8±\sqrt{64-4\left(-5\right)}}{2\left(-5\right)}
Square 8.
x=\frac{-8±\sqrt{64+20}}{2\left(-5\right)}
Multiply -4 times -5.
x=\frac{-8±\sqrt{84}}{2\left(-5\right)}
Add 64 to 20.
x=\frac{-8±2\sqrt{21}}{2\left(-5\right)}
Take the square root of 84.
x=\frac{-8±2\sqrt{21}}{-10}
Multiply 2 times -5.
x=\frac{2\sqrt{21}-8}{-10}
Now solve the equation x=\frac{-8±2\sqrt{21}}{-10} when ± is plus. Add -8 to 2\sqrt{21}.
x=\frac{4-\sqrt{21}}{5}
Divide -8+2\sqrt{21} by -10.
x=\frac{-2\sqrt{21}-8}{-10}
Now solve the equation x=\frac{-8±2\sqrt{21}}{-10} when ± is minus. Subtract 2\sqrt{21} from -8.
x=\frac{\sqrt{21}+4}{5}
Divide -8-2\sqrt{21} by -10.
x=\frac{4-\sqrt{21}}{5} x=\frac{\sqrt{21}+4}{5}
The equation is now solved.
2\left(x-1\right)\left(x+1\right)-\left(x+1\right)\left(x-3\right)=\left(2x-2\right)\times 3x
Variable x cannot be equal to any of the values -1,1 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-1\right)\left(x+1\right), the least common multiple of 2x-2,x+1.
\left(2x-2\right)\left(x+1\right)-\left(x+1\right)\left(x-3\right)=\left(2x-2\right)\times 3x
Use the distributive property to multiply 2 by x-1.
2x^{2}-2-\left(x+1\right)\left(x-3\right)=\left(2x-2\right)\times 3x
Use the distributive property to multiply 2x-2 by x+1 and combine like terms.
2x^{2}-2-\left(x^{2}-2x-3\right)=\left(2x-2\right)\times 3x
Use the distributive property to multiply x+1 by x-3 and combine like terms.
2x^{2}-2-x^{2}+2x+3=\left(2x-2\right)\times 3x
To find the opposite of x^{2}-2x-3, find the opposite of each term.
x^{2}-2+2x+3=\left(2x-2\right)\times 3x
Combine 2x^{2} and -x^{2} to get x^{2}.
x^{2}+1+2x=\left(2x-2\right)\times 3x
Add -2 and 3 to get 1.
x^{2}+1+2x=\left(6x-6\right)x
Use the distributive property to multiply 2x-2 by 3.
x^{2}+1+2x=6x^{2}-6x
Use the distributive property to multiply 6x-6 by x.
x^{2}+1+2x-6x^{2}=-6x
Subtract 6x^{2} from both sides.
-5x^{2}+1+2x=-6x
Combine x^{2} and -6x^{2} to get -5x^{2}.
-5x^{2}+1+2x+6x=0
Add 6x to both sides.
-5x^{2}+1+8x=0
Combine 2x and 6x to get 8x.
-5x^{2}+8x=-1
Subtract 1 from both sides. Anything subtracted from zero gives its negation.
\frac{-5x^{2}+8x}{-5}=-\frac{1}{-5}
Divide both sides by -5.
x^{2}+\frac{8}{-5}x=-\frac{1}{-5}
Dividing by -5 undoes the multiplication by -5.
x^{2}-\frac{8}{5}x=-\frac{1}{-5}
Divide 8 by -5.
x^{2}-\frac{8}{5}x=\frac{1}{5}
Divide -1 by -5.
x^{2}-\frac{8}{5}x+\left(-\frac{4}{5}\right)^{2}=\frac{1}{5}+\left(-\frac{4}{5}\right)^{2}
Divide -\frac{8}{5}, the coefficient of the x term, by 2 to get -\frac{4}{5}. Then add the square of -\frac{4}{5} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{8}{5}x+\frac{16}{25}=\frac{1}{5}+\frac{16}{25}
Square -\frac{4}{5} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{8}{5}x+\frac{16}{25}=\frac{21}{25}
Add \frac{1}{5} to \frac{16}{25} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{4}{5}\right)^{2}=\frac{21}{25}
Factor x^{2}-\frac{8}{5}x+\frac{16}{25}. 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{4}{5}\right)^{2}}=\sqrt{\frac{21}{25}}
Take the square root of both sides of the equation.
x-\frac{4}{5}=\frac{\sqrt{21}}{5} x-\frac{4}{5}=-\frac{\sqrt{21}}{5}
Simplify.
x=\frac{\sqrt{21}+4}{5} x=\frac{4-\sqrt{21}}{5}
Add \frac{4}{5} to both sides of the equation.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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Linear equation
y = 3x + 4
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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}