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20x^{2}=7\left(4\times 8+3\right)
Multiply both sides of the equation by 56, the least common multiple of 14,8.
20x^{2}=7\left(32+3\right)
Multiply 4 and 8 to get 32.
20x^{2}=7\times 35
Add 32 and 3 to get 35.
20x^{2}=245
Multiply 7 and 35 to get 245.
20x^{2}-245=0
Subtract 245 from both sides.
4x^{2}-49=0
Divide both sides by 5.
\left(2x-7\right)\left(2x+7\right)=0
Consider 4x^{2}-49. Rewrite 4x^{2}-49 as \left(2x\right)^{2}-7^{2}. The difference of squares can be factored using the rule: a^{2}-b^{2}=\left(a-b\right)\left(a+b\right).
x=\frac{7}{2} x=-\frac{7}{2}
To find equation solutions, solve 2x-7=0 and 2x+7=0.
20x^{2}=7\left(4\times 8+3\right)
Multiply both sides of the equation by 56, the least common multiple of 14,8.
20x^{2}=7\left(32+3\right)
Multiply 4 and 8 to get 32.
20x^{2}=7\times 35
Add 32 and 3 to get 35.
20x^{2}=245
Multiply 7 and 35 to get 245.
x^{2}=\frac{245}{20}
Divide both sides by 20.
x^{2}=\frac{49}{4}
Reduce the fraction \frac{245}{20} to lowest terms by extracting and canceling out 5.
x=\frac{7}{2} x=-\frac{7}{2}
Take the square root of both sides of the equation.
20x^{2}=7\left(4\times 8+3\right)
Multiply both sides of the equation by 56, the least common multiple of 14,8.
20x^{2}=7\left(32+3\right)
Multiply 4 and 8 to get 32.
20x^{2}=7\times 35
Add 32 and 3 to get 35.
20x^{2}=245
Multiply 7 and 35 to get 245.
20x^{2}-245=0
Subtract 245 from both sides.
x=\frac{0±\sqrt{0^{2}-4\times 20\left(-245\right)}}{2\times 20}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 20 for a, 0 for b, and -245 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\times 20\left(-245\right)}}{2\times 20}
Square 0.
x=\frac{0±\sqrt{-80\left(-245\right)}}{2\times 20}
Multiply -4 times 20.
x=\frac{0±\sqrt{19600}}{2\times 20}
Multiply -80 times -245.
x=\frac{0±140}{2\times 20}
Take the square root of 19600.
x=\frac{0±140}{40}
Multiply 2 times 20.
x=\frac{7}{2}
Now solve the equation x=\frac{0±140}{40} when ± is plus. Reduce the fraction \frac{140}{40} to lowest terms by extracting and canceling out 20.
x=-\frac{7}{2}
Now solve the equation x=\frac{0±140}{40} when ± is minus. Reduce the fraction \frac{-140}{40} to lowest terms by extracting and canceling out 20.
x=\frac{7}{2} x=-\frac{7}{2}
The equation is now solved.