Solve for y
y=2
y=\frac{4}{11}\approx 0.363636364
Graph
Share
Copied to clipboard
11y^{2}-26y+8=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=-26 ab=11\times 8=88
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as 11y^{2}+ay+by+8. To find a and b, set up a system to be solved.
-1,-88 -2,-44 -4,-22 -8,-11
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 88.
-1-88=-89 -2-44=-46 -4-22=-26 -8-11=-19
Calculate the sum for each pair.
a=-22 b=-4
The solution is the pair that gives sum -26.
\left(11y^{2}-22y\right)+\left(-4y+8\right)
Rewrite 11y^{2}-26y+8 as \left(11y^{2}-22y\right)+\left(-4y+8\right).
11y\left(y-2\right)-4\left(y-2\right)
Factor out 11y in the first and -4 in the second group.
\left(y-2\right)\left(11y-4\right)
Factor out common term y-2 by using distributive property.
y=2 y=\frac{4}{11}
To find equation solutions, solve y-2=0 and 11y-4=0.
11y^{2}-26y+8=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.
y=\frac{-\left(-26\right)±\sqrt{\left(-26\right)^{2}-4\times 11\times 8}}{2\times 11}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 11 for a, -26 for b, and 8 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
y=\frac{-\left(-26\right)±\sqrt{676-4\times 11\times 8}}{2\times 11}
Square -26.
y=\frac{-\left(-26\right)±\sqrt{676-44\times 8}}{2\times 11}
Multiply -4 times 11.
y=\frac{-\left(-26\right)±\sqrt{676-352}}{2\times 11}
Multiply -44 times 8.
y=\frac{-\left(-26\right)±\sqrt{324}}{2\times 11}
Add 676 to -352.
y=\frac{-\left(-26\right)±18}{2\times 11}
Take the square root of 324.
y=\frac{26±18}{2\times 11}
The opposite of -26 is 26.
y=\frac{26±18}{22}
Multiply 2 times 11.
y=\frac{44}{22}
Now solve the equation y=\frac{26±18}{22} when ± is plus. Add 26 to 18.
y=2
Divide 44 by 22.
y=\frac{8}{22}
Now solve the equation y=\frac{26±18}{22} when ± is minus. Subtract 18 from 26.
y=\frac{4}{11}
Reduce the fraction \frac{8}{22} to lowest terms by extracting and canceling out 2.
y=2 y=\frac{4}{11}
The equation is now solved.
11y^{2}-26y+8=0
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.
11y^{2}-26y+8-8=-8
Subtract 8 from both sides of the equation.
11y^{2}-26y=-8
Subtracting 8 from itself leaves 0.
\frac{11y^{2}-26y}{11}=-\frac{8}{11}
Divide both sides by 11.
y^{2}-\frac{26}{11}y=-\frac{8}{11}
Dividing by 11 undoes the multiplication by 11.
y^{2}-\frac{26}{11}y+\left(-\frac{13}{11}\right)^{2}=-\frac{8}{11}+\left(-\frac{13}{11}\right)^{2}
Divide -\frac{26}{11}, the coefficient of the x term, by 2 to get -\frac{13}{11}. Then add the square of -\frac{13}{11} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
y^{2}-\frac{26}{11}y+\frac{169}{121}=-\frac{8}{11}+\frac{169}{121}
Square -\frac{13}{11} by squaring both the numerator and the denominator of the fraction.
y^{2}-\frac{26}{11}y+\frac{169}{121}=\frac{81}{121}
Add -\frac{8}{11} to \frac{169}{121} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(y-\frac{13}{11}\right)^{2}=\frac{81}{121}
Factor y^{2}-\frac{26}{11}y+\frac{169}{121}. 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(y-\frac{13}{11}\right)^{2}}=\sqrt{\frac{81}{121}}
Take the square root of both sides of the equation.
y-\frac{13}{11}=\frac{9}{11} y-\frac{13}{11}=-\frac{9}{11}
Simplify.
y=2 y=\frac{4}{11}
Add \frac{13}{11} 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}