Solve for x
x=12
x=155
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Quadratic Equation
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\frac{ 2200 }{ 100-x } +15= \frac{ 22 \times 100 }{ 67-x }
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\left(67-x\right)\times 2200+\left(x-100\right)\left(x-67\right)\times 15=\left(100-x\right)\times 22\times 100
Variable x cannot be equal to any of the values 67,100 since division by zero is not defined. Multiply both sides of the equation by \left(x-100\right)\left(x-67\right), the least common multiple of 100-x,67-x.
147400-2200x+\left(x-100\right)\left(x-67\right)\times 15=\left(100-x\right)\times 22\times 100
Use the distributive property to multiply 67-x by 2200.
147400-2200x+\left(x^{2}-167x+6700\right)\times 15=\left(100-x\right)\times 22\times 100
Use the distributive property to multiply x-100 by x-67 and combine like terms.
147400-2200x+15x^{2}-2505x+100500=\left(100-x\right)\times 22\times 100
Use the distributive property to multiply x^{2}-167x+6700 by 15.
147400-4705x+15x^{2}+100500=\left(100-x\right)\times 22\times 100
Combine -2200x and -2505x to get -4705x.
247900-4705x+15x^{2}=\left(100-x\right)\times 22\times 100
Add 147400 and 100500 to get 247900.
247900-4705x+15x^{2}=\left(100-x\right)\times 2200
Multiply 22 and 100 to get 2200.
247900-4705x+15x^{2}=220000-2200x
Use the distributive property to multiply 100-x by 2200.
247900-4705x+15x^{2}-220000=-2200x
Subtract 220000 from both sides.
27900-4705x+15x^{2}=-2200x
Subtract 220000 from 247900 to get 27900.
27900-4705x+15x^{2}+2200x=0
Add 2200x to both sides.
27900-2505x+15x^{2}=0
Combine -4705x and 2200x to get -2505x.
15x^{2}-2505x+27900=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(-2505\right)±\sqrt{\left(-2505\right)^{2}-4\times 15\times 27900}}{2\times 15}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 15 for a, -2505 for b, and 27900 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-2505\right)±\sqrt{6275025-4\times 15\times 27900}}{2\times 15}
Square -2505.
x=\frac{-\left(-2505\right)±\sqrt{6275025-60\times 27900}}{2\times 15}
Multiply -4 times 15.
x=\frac{-\left(-2505\right)±\sqrt{6275025-1674000}}{2\times 15}
Multiply -60 times 27900.
x=\frac{-\left(-2505\right)±\sqrt{4601025}}{2\times 15}
Add 6275025 to -1674000.
x=\frac{-\left(-2505\right)±2145}{2\times 15}
Take the square root of 4601025.
x=\frac{2505±2145}{2\times 15}
The opposite of -2505 is 2505.
x=\frac{2505±2145}{30}
Multiply 2 times 15.
x=\frac{4650}{30}
Now solve the equation x=\frac{2505±2145}{30} when ± is plus. Add 2505 to 2145.
x=155
Divide 4650 by 30.
x=\frac{360}{30}
Now solve the equation x=\frac{2505±2145}{30} when ± is minus. Subtract 2145 from 2505.
x=12
Divide 360 by 30.
x=155 x=12
The equation is now solved.
\left(67-x\right)\times 2200+\left(x-100\right)\left(x-67\right)\times 15=\left(100-x\right)\times 22\times 100
Variable x cannot be equal to any of the values 67,100 since division by zero is not defined. Multiply both sides of the equation by \left(x-100\right)\left(x-67\right), the least common multiple of 100-x,67-x.
147400-2200x+\left(x-100\right)\left(x-67\right)\times 15=\left(100-x\right)\times 22\times 100
Use the distributive property to multiply 67-x by 2200.
147400-2200x+\left(x^{2}-167x+6700\right)\times 15=\left(100-x\right)\times 22\times 100
Use the distributive property to multiply x-100 by x-67 and combine like terms.
147400-2200x+15x^{2}-2505x+100500=\left(100-x\right)\times 22\times 100
Use the distributive property to multiply x^{2}-167x+6700 by 15.
147400-4705x+15x^{2}+100500=\left(100-x\right)\times 22\times 100
Combine -2200x and -2505x to get -4705x.
247900-4705x+15x^{2}=\left(100-x\right)\times 22\times 100
Add 147400 and 100500 to get 247900.
247900-4705x+15x^{2}=\left(100-x\right)\times 2200
Multiply 22 and 100 to get 2200.
247900-4705x+15x^{2}=220000-2200x
Use the distributive property to multiply 100-x by 2200.
247900-4705x+15x^{2}+2200x=220000
Add 2200x to both sides.
247900-2505x+15x^{2}=220000
Combine -4705x and 2200x to get -2505x.
-2505x+15x^{2}=220000-247900
Subtract 247900 from both sides.
-2505x+15x^{2}=-27900
Subtract 247900 from 220000 to get -27900.
15x^{2}-2505x=-27900
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{15x^{2}-2505x}{15}=-\frac{27900}{15}
Divide both sides by 15.
x^{2}+\left(-\frac{2505}{15}\right)x=-\frac{27900}{15}
Dividing by 15 undoes the multiplication by 15.
x^{2}-167x=-\frac{27900}{15}
Divide -2505 by 15.
x^{2}-167x=-1860
Divide -27900 by 15.
x^{2}-167x+\left(-\frac{167}{2}\right)^{2}=-1860+\left(-\frac{167}{2}\right)^{2}
Divide -167, the coefficient of the x term, by 2 to get -\frac{167}{2}. Then add the square of -\frac{167}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-167x+\frac{27889}{4}=-1860+\frac{27889}{4}
Square -\frac{167}{2} by squaring both the numerator and the denominator of the fraction.
x^{2}-167x+\frac{27889}{4}=\frac{20449}{4}
Add -1860 to \frac{27889}{4}.
\left(x-\frac{167}{2}\right)^{2}=\frac{20449}{4}
Factor x^{2}-167x+\frac{27889}{4}. 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{167}{2}\right)^{2}}=\sqrt{\frac{20449}{4}}
Take the square root of both sides of the equation.
x-\frac{167}{2}=\frac{143}{2} x-\frac{167}{2}=-\frac{143}{2}
Simplify.
x=155 x=12
Add \frac{167}{2} to both sides of the equation.
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