Skip to main content
Solve for x
Tick mark Image
Graph

Similar Problems from Web Search

Share

5+x\times 6=xx-2
Variable x cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by x.
5+x\times 6=x^{2}-2
Multiply x and x to get x^{2}.
5+x\times 6-x^{2}=-2
Subtract x^{2} from both sides.
5+x\times 6-x^{2}+2=0
Add 2 to both sides.
7+x\times 6-x^{2}=0
Add 5 and 2 to get 7.
-x^{2}+6x+7=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{-6±\sqrt{6^{2}-4\left(-1\right)\times 7}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, 6 for b, and 7 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-6±\sqrt{36-4\left(-1\right)\times 7}}{2\left(-1\right)}
Square 6.
x=\frac{-6±\sqrt{36+4\times 7}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{-6±\sqrt{36+28}}{2\left(-1\right)}
Multiply 4 times 7.
x=\frac{-6±\sqrt{64}}{2\left(-1\right)}
Add 36 to 28.
x=\frac{-6±8}{2\left(-1\right)}
Take the square root of 64.
x=\frac{-6±8}{-2}
Multiply 2 times -1.
x=\frac{2}{-2}
Now solve the equation x=\frac{-6±8}{-2} when ± is plus. Add -6 to 8.
x=-1
Divide 2 by -2.
x=-\frac{14}{-2}
Now solve the equation x=\frac{-6±8}{-2} when ± is minus. Subtract 8 from -6.
x=7
Divide -14 by -2.
x=-1 x=7
The equation is now solved.
5+x\times 6=xx-2
Variable x cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by x.
5+x\times 6=x^{2}-2
Multiply x and x to get x^{2}.
5+x\times 6-x^{2}=-2
Subtract x^{2} from both sides.
x\times 6-x^{2}=-2-5
Subtract 5 from both sides.
x\times 6-x^{2}=-7
Subtract 5 from -2 to get -7.
-x^{2}+6x=-7
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}+6x}{-1}=-\frac{7}{-1}
Divide both sides by -1.
x^{2}+\frac{6}{-1}x=-\frac{7}{-1}
Dividing by -1 undoes the multiplication by -1.
x^{2}-6x=-\frac{7}{-1}
Divide 6 by -1.
x^{2}-6x=7
Divide -7 by -1.
x^{2}-6x+\left(-3\right)^{2}=7+\left(-3\right)^{2}
Divide -6, the coefficient of the x term, by 2 to get -3. Then add the square of -3 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-6x+9=7+9
Square -3.
x^{2}-6x+9=16
Add 7 to 9.
\left(x-3\right)^{2}=16
Factor x^{2}-6x+9. 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-3\right)^{2}}=\sqrt{16}
Take the square root of both sides of the equation.
x-3=4 x-3=-4
Simplify.
x=7 x=-1
Add 3 to both sides of the equation.