Solve for x
x=-1
x = \frac{7}{2} = 3\frac{1}{2} = 3.5
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2x^{2}-5x-3=4
Use the distributive property to multiply x-3 by 2x+1 and combine like terms.
2x^{2}-5x-3-4=0
Subtract 4 from both sides.
2x^{2}-5x-7=0
Subtract 4 from -3 to get -7.
x=\frac{-\left(-5\right)±\sqrt{\left(-5\right)^{2}-4\times 2\left(-7\right)}}{2\times 2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 2 for a, -5 for b, and -7 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-5\right)±\sqrt{25-4\times 2\left(-7\right)}}{2\times 2}
Square -5.
x=\frac{-\left(-5\right)±\sqrt{25-8\left(-7\right)}}{2\times 2}
Multiply -4 times 2.
x=\frac{-\left(-5\right)±\sqrt{25+56}}{2\times 2}
Multiply -8 times -7.
x=\frac{-\left(-5\right)±\sqrt{81}}{2\times 2}
Add 25 to 56.
x=\frac{-\left(-5\right)±9}{2\times 2}
Take the square root of 81.
x=\frac{5±9}{2\times 2}
The opposite of -5 is 5.
x=\frac{5±9}{4}
Multiply 2 times 2.
x=\frac{14}{4}
Now solve the equation x=\frac{5±9}{4} when ± is plus. Add 5 to 9.
x=\frac{7}{2}
Reduce the fraction \frac{14}{4} to lowest terms by extracting and canceling out 2.
x=-\frac{4}{4}
Now solve the equation x=\frac{5±9}{4} when ± is minus. Subtract 9 from 5.
x=-1
Divide -4 by 4.
x=\frac{7}{2} x=-1
The equation is now solved.
2x^{2}-5x-3=4
Use the distributive property to multiply x-3 by 2x+1 and combine like terms.
2x^{2}-5x=4+3
Add 3 to both sides.
2x^{2}-5x=7
Add 4 and 3 to get 7.
\frac{2x^{2}-5x}{2}=\frac{7}{2}
Divide both sides by 2.
x^{2}-\frac{5}{2}x=\frac{7}{2}
Dividing by 2 undoes the multiplication by 2.
x^{2}-\frac{5}{2}x+\left(-\frac{5}{4}\right)^{2}=\frac{7}{2}+\left(-\frac{5}{4}\right)^{2}
Divide -\frac{5}{2}, the coefficient of the x term, by 2 to get -\frac{5}{4}. Then add the square of -\frac{5}{4} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{5}{2}x+\frac{25}{16}=\frac{7}{2}+\frac{25}{16}
Square -\frac{5}{4} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{5}{2}x+\frac{25}{16}=\frac{81}{16}
Add \frac{7}{2} to \frac{25}{16} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{5}{4}\right)^{2}=\frac{81}{16}
Factor x^{2}-\frac{5}{2}x+\frac{25}{16}. 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{5}{4}\right)^{2}}=\sqrt{\frac{81}{16}}
Take the square root of both sides of the equation.
x-\frac{5}{4}=\frac{9}{4} x-\frac{5}{4}=-\frac{9}{4}
Simplify.
x=\frac{7}{2} x=-1
Add \frac{5}{4} 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}