Skip to main content
Solve for x
Tick mark Image
Graph

Similar Problems from Web Search

Share

2128=\left(4+6\left(x-1\right)\right)x
Multiply both sides of the equation by 2.
2128=\left(4+6x-6\right)x
Use the distributive property to multiply 6 by x-1.
2128=\left(-2+6x\right)x
Subtract 6 from 4 to get -2.
2128=-2x+6x^{2}
Use the distributive property to multiply -2+6x by x.
-2x+6x^{2}=2128
Swap sides so that all variable terms are on the left hand side.
-2x+6x^{2}-2128=0
Subtract 2128 from both sides.
6x^{2}-2x-2128=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{-\left(-2\right)±\sqrt{\left(-2\right)^{2}-4\times 6\left(-2128\right)}}{2\times 6}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 6 for a, -2 for b, and -2128 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-2\right)±\sqrt{4-4\times 6\left(-2128\right)}}{2\times 6}
Square -2.
x=\frac{-\left(-2\right)±\sqrt{4-24\left(-2128\right)}}{2\times 6}
Multiply -4 times 6.
x=\frac{-\left(-2\right)±\sqrt{4+51072}}{2\times 6}
Multiply -24 times -2128.
x=\frac{-\left(-2\right)±\sqrt{51076}}{2\times 6}
Add 4 to 51072.
x=\frac{-\left(-2\right)±226}{2\times 6}
Take the square root of 51076.
x=\frac{2±226}{2\times 6}
The opposite of -2 is 2.
x=\frac{2±226}{12}
Multiply 2 times 6.
x=\frac{228}{12}
Now solve the equation x=\frac{2±226}{12} when ± is plus. Add 2 to 226.
x=19
Divide 228 by 12.
x=-\frac{224}{12}
Now solve the equation x=\frac{2±226}{12} when ± is minus. Subtract 226 from 2.
x=-\frac{56}{3}
Reduce the fraction \frac{-224}{12} to lowest terms by extracting and canceling out 4.
x=19 x=-\frac{56}{3}
The equation is now solved.
2128=\left(4+6\left(x-1\right)\right)x
Multiply both sides of the equation by 2.
2128=\left(4+6x-6\right)x
Use the distributive property to multiply 6 by x-1.
2128=\left(-2+6x\right)x
Subtract 6 from 4 to get -2.
2128=-2x+6x^{2}
Use the distributive property to multiply -2+6x by x.
-2x+6x^{2}=2128
Swap sides so that all variable terms are on the left hand side.
6x^{2}-2x=2128
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{6x^{2}-2x}{6}=\frac{2128}{6}
Divide both sides by 6.
x^{2}+\left(-\frac{2}{6}\right)x=\frac{2128}{6}
Dividing by 6 undoes the multiplication by 6.
x^{2}-\frac{1}{3}x=\frac{2128}{6}
Reduce the fraction \frac{-2}{6} to lowest terms by extracting and canceling out 2.
x^{2}-\frac{1}{3}x=\frac{1064}{3}
Reduce the fraction \frac{2128}{6} to lowest terms by extracting and canceling out 2.
x^{2}-\frac{1}{3}x+\left(-\frac{1}{6}\right)^{2}=\frac{1064}{3}+\left(-\frac{1}{6}\right)^{2}
Divide -\frac{1}{3}, the coefficient of the x term, by 2 to get -\frac{1}{6}. Then add the square of -\frac{1}{6} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{1}{3}x+\frac{1}{36}=\frac{1064}{3}+\frac{1}{36}
Square -\frac{1}{6} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{1}{3}x+\frac{1}{36}=\frac{12769}{36}
Add \frac{1064}{3} to \frac{1}{36} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{1}{6}\right)^{2}=\frac{12769}{36}
Factor x^{2}-\frac{1}{3}x+\frac{1}{36}. 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{1}{6}\right)^{2}}=\sqrt{\frac{12769}{36}}
Take the square root of both sides of the equation.
x-\frac{1}{6}=\frac{113}{6} x-\frac{1}{6}=-\frac{113}{6}
Simplify.
x=19 x=-\frac{56}{3}
Add \frac{1}{6} to both sides of the equation.