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\left(\sqrt{\left(3x+42\right)x}\right)^{2}=x+14
Use the distributive property to multiply x+14 by 3.
\left(\sqrt{3x^{2}+42x}\right)^{2}=x+14
Use the distributive property to multiply 3x+42 by x.
3x^{2}+42x=x+14
Calculate \sqrt{3x^{2}+42x} to the power of 2 and get 3x^{2}+42x.
3x^{2}+42x-x=14
Subtract x from both sides.
3x^{2}+41x=14
Combine 42x and -x to get 41x.
3x^{2}+41x-14=0
Subtract 14 from both sides.
a+b=41 ab=3\left(-14\right)=-42
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as 3x^{2}+ax+bx-14. To find a and b, set up a system to be solved.
-1,42 -2,21 -3,14 -6,7
Since ab is negative, a and b have the opposite signs. Since a+b is positive, the positive number has greater absolute value than the negative. List all such integer pairs that give product -42.
-1+42=41 -2+21=19 -3+14=11 -6+7=1
Calculate the sum for each pair.
a=-1 b=42
The solution is the pair that gives sum 41.
\left(3x^{2}-x\right)+\left(42x-14\right)
Rewrite 3x^{2}+41x-14 as \left(3x^{2}-x\right)+\left(42x-14\right).
x\left(3x-1\right)+14\left(3x-1\right)
Factor out x in the first and 14 in the second group.
\left(3x-1\right)\left(x+14\right)
Factor out common term 3x-1 by using distributive property.
x=\frac{1}{3} x=-14
To find equation solutions, solve 3x-1=0 and x+14=0.
\left(\sqrt{\left(3x+42\right)x}\right)^{2}=x+14
Use the distributive property to multiply x+14 by 3.
\left(\sqrt{3x^{2}+42x}\right)^{2}=x+14
Use the distributive property to multiply 3x+42 by x.
3x^{2}+42x=x+14
Calculate \sqrt{3x^{2}+42x} to the power of 2 and get 3x^{2}+42x.
3x^{2}+42x-x=14
Subtract x from both sides.
3x^{2}+41x=14
Combine 42x and -x to get 41x.
3x^{2}+41x-14=0
Subtract 14 from both sides.
x=\frac{-41±\sqrt{41^{2}-4\times 3\left(-14\right)}}{2\times 3}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 3 for a, 41 for b, and -14 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-41±\sqrt{1681-4\times 3\left(-14\right)}}{2\times 3}
Square 41.
x=\frac{-41±\sqrt{1681-12\left(-14\right)}}{2\times 3}
Multiply -4 times 3.
x=\frac{-41±\sqrt{1681+168}}{2\times 3}
Multiply -12 times -14.
x=\frac{-41±\sqrt{1849}}{2\times 3}
Add 1681 to 168.
x=\frac{-41±43}{2\times 3}
Take the square root of 1849.
x=\frac{-41±43}{6}
Multiply 2 times 3.
x=\frac{2}{6}
Now solve the equation x=\frac{-41±43}{6} when ± is plus. Add -41 to 43.
x=\frac{1}{3}
Reduce the fraction \frac{2}{6} to lowest terms by extracting and canceling out 2.
x=-\frac{84}{6}
Now solve the equation x=\frac{-41±43}{6} when ± is minus. Subtract 43 from -41.
x=-14
Divide -84 by 6.
x=\frac{1}{3} x=-14
The equation is now solved.
\left(\sqrt{\left(3x+42\right)x}\right)^{2}=x+14
Use the distributive property to multiply x+14 by 3.
\left(\sqrt{3x^{2}+42x}\right)^{2}=x+14
Use the distributive property to multiply 3x+42 by x.
3x^{2}+42x=x+14
Calculate \sqrt{3x^{2}+42x} to the power of 2 and get 3x^{2}+42x.
3x^{2}+42x-x=14
Subtract x from both sides.
3x^{2}+41x=14
Combine 42x and -x to get 41x.
\frac{3x^{2}+41x}{3}=\frac{14}{3}
Divide both sides by 3.
x^{2}+\frac{41}{3}x=\frac{14}{3}
Dividing by 3 undoes the multiplication by 3.
x^{2}+\frac{41}{3}x+\left(\frac{41}{6}\right)^{2}=\frac{14}{3}+\left(\frac{41}{6}\right)^{2}
Divide \frac{41}{3}, the coefficient of the x term, by 2 to get \frac{41}{6}. Then add the square of \frac{41}{6} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+\frac{41}{3}x+\frac{1681}{36}=\frac{14}{3}+\frac{1681}{36}
Square \frac{41}{6} by squaring both the numerator and the denominator of the fraction.
x^{2}+\frac{41}{3}x+\frac{1681}{36}=\frac{1849}{36}
Add \frac{14}{3} to \frac{1681}{36} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x+\frac{41}{6}\right)^{2}=\frac{1849}{36}
Factor x^{2}+\frac{41}{3}x+\frac{1681}{36}. 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{41}{6}\right)^{2}}=\sqrt{\frac{1849}{36}}
Take the square root of both sides of the equation.
x+\frac{41}{6}=\frac{43}{6} x+\frac{41}{6}=-\frac{43}{6}
Simplify.
x=\frac{1}{3} x=-14
Subtract \frac{41}{6} from both sides of the equation.