Solve for a
a=-9
Share
Copied to clipboard
\left(a-1\right)\left(2a-3\right)+\left(a+2\right)\left(a+2\right)=\left(a+2\right)\left(a+2\right)+\left(a-1\right)\left(a+2\right)\times 3
Variable a cannot be equal to any of the values -2,1 since division by zero is not defined. Multiply both sides of the equation by \left(a-1\right)\left(a+2\right), the least common multiple of a+2,a-1.
\left(a-1\right)\left(2a-3\right)+\left(a+2\right)^{2}=\left(a+2\right)\left(a+2\right)+\left(a-1\right)\left(a+2\right)\times 3
Multiply a+2 and a+2 to get \left(a+2\right)^{2}.
\left(a-1\right)\left(2a-3\right)+\left(a+2\right)^{2}=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Multiply a+2 and a+2 to get \left(a+2\right)^{2}.
2a^{2}-5a+3+\left(a+2\right)^{2}=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Use the distributive property to multiply a-1 by 2a-3 and combine like terms.
2a^{2}-5a+3+a^{2}+4a+4=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(a+2\right)^{2}.
3a^{2}-5a+3+4a+4=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Combine 2a^{2} and a^{2} to get 3a^{2}.
3a^{2}-a+3+4=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Combine -5a and 4a to get -a.
3a^{2}-a+7=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Add 3 and 4 to get 7.
3a^{2}-a+7=a^{2}+4a+4+\left(a-1\right)\left(a+2\right)\times 3
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(a+2\right)^{2}.
3a^{2}-a+7=a^{2}+4a+4+\left(a^{2}+a-2\right)\times 3
Use the distributive property to multiply a-1 by a+2 and combine like terms.
3a^{2}-a+7=a^{2}+4a+4+3a^{2}+3a-6
Use the distributive property to multiply a^{2}+a-2 by 3.
3a^{2}-a+7=4a^{2}+4a+4+3a-6
Combine a^{2} and 3a^{2} to get 4a^{2}.
3a^{2}-a+7=4a^{2}+7a+4-6
Combine 4a and 3a to get 7a.
3a^{2}-a+7=4a^{2}+7a-2
Subtract 6 from 4 to get -2.
3a^{2}-a+7-4a^{2}=7a-2
Subtract 4a^{2} from both sides.
-a^{2}-a+7=7a-2
Combine 3a^{2} and -4a^{2} to get -a^{2}.
-a^{2}-a+7-7a=-2
Subtract 7a from both sides.
-a^{2}-8a+7=-2
Combine -a and -7a to get -8a.
-a^{2}-8a+7+2=0
Add 2 to both sides.
-a^{2}-8a+9=0
Add 7 and 2 to get 9.
a=\frac{-\left(-8\right)±\sqrt{\left(-8\right)^{2}-4\left(-1\right)\times 9}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, -8 for b, and 9 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
a=\frac{-\left(-8\right)±\sqrt{64-4\left(-1\right)\times 9}}{2\left(-1\right)}
Square -8.
a=\frac{-\left(-8\right)±\sqrt{64+4\times 9}}{2\left(-1\right)}
Multiply -4 times -1.
a=\frac{-\left(-8\right)±\sqrt{64+36}}{2\left(-1\right)}
Multiply 4 times 9.
a=\frac{-\left(-8\right)±\sqrt{100}}{2\left(-1\right)}
Add 64 to 36.
a=\frac{-\left(-8\right)±10}{2\left(-1\right)}
Take the square root of 100.
a=\frac{8±10}{2\left(-1\right)}
The opposite of -8 is 8.
a=\frac{8±10}{-2}
Multiply 2 times -1.
a=\frac{18}{-2}
Now solve the equation a=\frac{8±10}{-2} when ± is plus. Add 8 to 10.
a=-9
Divide 18 by -2.
a=-\frac{2}{-2}
Now solve the equation a=\frac{8±10}{-2} when ± is minus. Subtract 10 from 8.
a=1
Divide -2 by -2.
a=-9 a=1
The equation is now solved.
a=-9
Variable a cannot be equal to 1.
\left(a-1\right)\left(2a-3\right)+\left(a+2\right)\left(a+2\right)=\left(a+2\right)\left(a+2\right)+\left(a-1\right)\left(a+2\right)\times 3
Variable a cannot be equal to any of the values -2,1 since division by zero is not defined. Multiply both sides of the equation by \left(a-1\right)\left(a+2\right), the least common multiple of a+2,a-1.
\left(a-1\right)\left(2a-3\right)+\left(a+2\right)^{2}=\left(a+2\right)\left(a+2\right)+\left(a-1\right)\left(a+2\right)\times 3
Multiply a+2 and a+2 to get \left(a+2\right)^{2}.
\left(a-1\right)\left(2a-3\right)+\left(a+2\right)^{2}=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Multiply a+2 and a+2 to get \left(a+2\right)^{2}.
2a^{2}-5a+3+\left(a+2\right)^{2}=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Use the distributive property to multiply a-1 by 2a-3 and combine like terms.
2a^{2}-5a+3+a^{2}+4a+4=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(a+2\right)^{2}.
3a^{2}-5a+3+4a+4=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Combine 2a^{2} and a^{2} to get 3a^{2}.
3a^{2}-a+3+4=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Combine -5a and 4a to get -a.
3a^{2}-a+7=\left(a+2\right)^{2}+\left(a-1\right)\left(a+2\right)\times 3
Add 3 and 4 to get 7.
3a^{2}-a+7=a^{2}+4a+4+\left(a-1\right)\left(a+2\right)\times 3
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(a+2\right)^{2}.
3a^{2}-a+7=a^{2}+4a+4+\left(a^{2}+a-2\right)\times 3
Use the distributive property to multiply a-1 by a+2 and combine like terms.
3a^{2}-a+7=a^{2}+4a+4+3a^{2}+3a-6
Use the distributive property to multiply a^{2}+a-2 by 3.
3a^{2}-a+7=4a^{2}+4a+4+3a-6
Combine a^{2} and 3a^{2} to get 4a^{2}.
3a^{2}-a+7=4a^{2}+7a+4-6
Combine 4a and 3a to get 7a.
3a^{2}-a+7=4a^{2}+7a-2
Subtract 6 from 4 to get -2.
3a^{2}-a+7-4a^{2}=7a-2
Subtract 4a^{2} from both sides.
-a^{2}-a+7=7a-2
Combine 3a^{2} and -4a^{2} to get -a^{2}.
-a^{2}-a+7-7a=-2
Subtract 7a from both sides.
-a^{2}-8a+7=-2
Combine -a and -7a to get -8a.
-a^{2}-8a=-2-7
Subtract 7 from both sides.
-a^{2}-8a=-9
Subtract 7 from -2 to get -9.
\frac{-a^{2}-8a}{-1}=-\frac{9}{-1}
Divide both sides by -1.
a^{2}+\left(-\frac{8}{-1}\right)a=-\frac{9}{-1}
Dividing by -1 undoes the multiplication by -1.
a^{2}+8a=-\frac{9}{-1}
Divide -8 by -1.
a^{2}+8a=9
Divide -9 by -1.
a^{2}+8a+4^{2}=9+4^{2}
Divide 8, the coefficient of the x term, by 2 to get 4. Then add the square of 4 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
a^{2}+8a+16=9+16
Square 4.
a^{2}+8a+16=25
Add 9 to 16.
\left(a+4\right)^{2}=25
Factor a^{2}+8a+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(a+4\right)^{2}}=\sqrt{25}
Take the square root of both sides of the equation.
a+4=5 a+4=-5
Simplify.
a=1 a=-9
Subtract 4 from both sides of the equation.
a=-9
Variable a cannot be equal to 1.
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}