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Solve for b (complex solution)
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Solve for b
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2b=4+6-b^{2}
Variable b cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by 4b, the least common multiple of 2,4b.
2b=10-b^{2}
Add 4 and 6 to get 10.
2b-10=-b^{2}
Subtract 10 from both sides.
2b-10+b^{2}=0
Add b^{2} to both sides.
b^{2}+2b-10=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.
b=\frac{-2±\sqrt{2^{2}-4\left(-10\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 2 for b, and -10 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
b=\frac{-2±\sqrt{4-4\left(-10\right)}}{2}
Square 2.
b=\frac{-2±\sqrt{4+40}}{2}
Multiply -4 times -10.
b=\frac{-2±\sqrt{44}}{2}
Add 4 to 40.
b=\frac{-2±2\sqrt{11}}{2}
Take the square root of 44.
b=\frac{2\sqrt{11}-2}{2}
Now solve the equation b=\frac{-2±2\sqrt{11}}{2} when ± is plus. Add -2 to 2\sqrt{11}.
b=\sqrt{11}-1
Divide -2+2\sqrt{11} by 2.
b=\frac{-2\sqrt{11}-2}{2}
Now solve the equation b=\frac{-2±2\sqrt{11}}{2} when ± is minus. Subtract 2\sqrt{11} from -2.
b=-\sqrt{11}-1
Divide -2-2\sqrt{11} by 2.
b=\sqrt{11}-1 b=-\sqrt{11}-1
The equation is now solved.
2b=4+6-b^{2}
Variable b cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by 4b, the least common multiple of 2,4b.
2b=10-b^{2}
Add 4 and 6 to get 10.
2b+b^{2}=10
Add b^{2} to both sides.
b^{2}+2b=10
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.
b^{2}+2b+1^{2}=10+1^{2}
Divide 2, the coefficient of the x term, by 2 to get 1. Then add the square of 1 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
b^{2}+2b+1=10+1
Square 1.
b^{2}+2b+1=11
Add 10 to 1.
\left(b+1\right)^{2}=11
Factor b^{2}+2b+1. 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(b+1\right)^{2}}=\sqrt{11}
Take the square root of both sides of the equation.
b+1=\sqrt{11} b+1=-\sqrt{11}
Simplify.
b=\sqrt{11}-1 b=-\sqrt{11}-1
Subtract 1 from both sides of the equation.
2b=4+6-b^{2}
Variable b cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by 4b, the least common multiple of 2,4b.
2b=10-b^{2}
Add 4 and 6 to get 10.
2b-10=-b^{2}
Subtract 10 from both sides.
2b-10+b^{2}=0
Add b^{2} to both sides.
b^{2}+2b-10=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.
b=\frac{-2±\sqrt{2^{2}-4\left(-10\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 2 for b, and -10 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
b=\frac{-2±\sqrt{4-4\left(-10\right)}}{2}
Square 2.
b=\frac{-2±\sqrt{4+40}}{2}
Multiply -4 times -10.
b=\frac{-2±\sqrt{44}}{2}
Add 4 to 40.
b=\frac{-2±2\sqrt{11}}{2}
Take the square root of 44.
b=\frac{2\sqrt{11}-2}{2}
Now solve the equation b=\frac{-2±2\sqrt{11}}{2} when ± is plus. Add -2 to 2\sqrt{11}.
b=\sqrt{11}-1
Divide -2+2\sqrt{11} by 2.
b=\frac{-2\sqrt{11}-2}{2}
Now solve the equation b=\frac{-2±2\sqrt{11}}{2} when ± is minus. Subtract 2\sqrt{11} from -2.
b=-\sqrt{11}-1
Divide -2-2\sqrt{11} by 2.
b=\sqrt{11}-1 b=-\sqrt{11}-1
The equation is now solved.
2b=4+6-b^{2}
Variable b cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by 4b, the least common multiple of 2,4b.
2b=10-b^{2}
Add 4 and 6 to get 10.
2b+b^{2}=10
Add b^{2} to both sides.
b^{2}+2b=10
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.
b^{2}+2b+1^{2}=10+1^{2}
Divide 2, the coefficient of the x term, by 2 to get 1. Then add the square of 1 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
b^{2}+2b+1=10+1
Square 1.
b^{2}+2b+1=11
Add 10 to 1.
\left(b+1\right)^{2}=11
Factor b^{2}+2b+1. 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(b+1\right)^{2}}=\sqrt{11}
Take the square root of both sides of the equation.
b+1=\sqrt{11} b+1=-\sqrt{11}
Simplify.
b=\sqrt{11}-1 b=-\sqrt{11}-1
Subtract 1 from both sides of the equation.