Solve for x
x=\frac{1}{2}=0.5
x=3
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2x^{2}-7x=-3
Subtract 7x from both sides.
2x^{2}-7x+3=0
Add 3 to both sides.
a+b=-7 ab=2\times 3=6
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as 2x^{2}+ax+bx+3. To find a and b, set up a system to be solved.
-1,-6 -2,-3
Since ab is positive, a and b have the same sign. Since a+b is negative, a and b are both negative. List all such integer pairs that give product 6.
-1-6=-7 -2-3=-5
Calculate the sum for each pair.
a=-6 b=-1
The solution is the pair that gives sum -7.
\left(2x^{2}-6x\right)+\left(-x+3\right)
Rewrite 2x^{2}-7x+3 as \left(2x^{2}-6x\right)+\left(-x+3\right).
2x\left(x-3\right)-\left(x-3\right)
Factor out 2x in the first and -1 in the second group.
\left(x-3\right)\left(2x-1\right)
Factor out common term x-3 by using distributive property.
x=3 x=\frac{1}{2}
To find equation solutions, solve x-3=0 and 2x-1=0.
2x^{2}-7x=-3
Subtract 7x from both sides.
2x^{2}-7x+3=0
Add 3 to both sides.
x=\frac{-\left(-7\right)±\sqrt{\left(-7\right)^{2}-4\times 2\times 3}}{2\times 2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 2 for a, -7 for b, and 3 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-7\right)±\sqrt{49-4\times 2\times 3}}{2\times 2}
Square -7.
x=\frac{-\left(-7\right)±\sqrt{49-8\times 3}}{2\times 2}
Multiply -4 times 2.
x=\frac{-\left(-7\right)±\sqrt{49-24}}{2\times 2}
Multiply -8 times 3.
x=\frac{-\left(-7\right)±\sqrt{25}}{2\times 2}
Add 49 to -24.
x=\frac{-\left(-7\right)±5}{2\times 2}
Take the square root of 25.
x=\frac{7±5}{2\times 2}
The opposite of -7 is 7.
x=\frac{7±5}{4}
Multiply 2 times 2.
x=\frac{12}{4}
Now solve the equation x=\frac{7±5}{4} when ± is plus. Add 7 to 5.
x=3
Divide 12 by 4.
x=\frac{2}{4}
Now solve the equation x=\frac{7±5}{4} when ± is minus. Subtract 5 from 7.
x=\frac{1}{2}
Reduce the fraction \frac{2}{4} to lowest terms by extracting and canceling out 2.
x=3 x=\frac{1}{2}
The equation is now solved.
2x^{2}-7x=-3
Subtract 7x from both sides.
\frac{2x^{2}-7x}{2}=-\frac{3}{2}
Divide both sides by 2.
x^{2}-\frac{7}{2}x=-\frac{3}{2}
Dividing by 2 undoes the multiplication by 2.
x^{2}-\frac{7}{2}x+\left(-\frac{7}{4}\right)^{2}=-\frac{3}{2}+\left(-\frac{7}{4}\right)^{2}
Divide -\frac{7}{2}, the coefficient of the x term, by 2 to get -\frac{7}{4}. Then add the square of -\frac{7}{4} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{7}{2}x+\frac{49}{16}=-\frac{3}{2}+\frac{49}{16}
Square -\frac{7}{4} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{7}{2}x+\frac{49}{16}=\frac{25}{16}
Add -\frac{3}{2} to \frac{49}{16} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{7}{4}\right)^{2}=\frac{25}{16}
Factor x^{2}-\frac{7}{2}x+\frac{49}{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{7}{4}\right)^{2}}=\sqrt{\frac{25}{16}}
Take the square root of both sides of the equation.
x-\frac{7}{4}=\frac{5}{4} x-\frac{7}{4}=-\frac{5}{4}
Simplify.
x=3 x=\frac{1}{2}
Add \frac{7}{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}