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\left(\sqrt{1^{2}+3-k}\right)^{2}=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Subtract 2 from 3 to get 1.
\left(\sqrt{1+3-k}\right)^{2}=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Calculate 1 to the power of 2 and get 1.
\left(\sqrt{4-k}\right)^{2}=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Add 1 and 3 to get 4.
4-k=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Calculate \sqrt{4-k} to the power of 2 and get 4-k.
4-k=\left(\sqrt{2^{2}+\left(2-k\right)^{2}}\right)^{2}
Subtract 2 from 4 to get 2.
4-k=\left(\sqrt{4+\left(2-k\right)^{2}}\right)^{2}
Calculate 2 to the power of 2 and get 4.
4-k=\left(\sqrt{4+4-4k+k^{2}}\right)^{2}
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(2-k\right)^{2}.
4-k=\left(\sqrt{8-4k+k^{2}}\right)^{2}
Add 4 and 4 to get 8.
4-k=8-4k+k^{2}
Calculate \sqrt{8-4k+k^{2}} to the power of 2 and get 8-4k+k^{2}.
4-k-8=-4k+k^{2}
Subtract 8 from both sides.
-4-k=-4k+k^{2}
Subtract 8 from 4 to get -4.
-4-k+4k=k^{2}
Add 4k to both sides.
-4+3k=k^{2}
Combine -k and 4k to get 3k.
-4+3k-k^{2}=0
Subtract k^{2} from both sides.
-k^{2}+3k-4=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.
k=\frac{-3±\sqrt{3^{2}-4\left(-1\right)\left(-4\right)}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, 3 for b, and -4 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
k=\frac{-3±\sqrt{9-4\left(-1\right)\left(-4\right)}}{2\left(-1\right)}
Square 3.
k=\frac{-3±\sqrt{9+4\left(-4\right)}}{2\left(-1\right)}
Multiply -4 times -1.
k=\frac{-3±\sqrt{9-16}}{2\left(-1\right)}
Multiply 4 times -4.
k=\frac{-3±\sqrt{-7}}{2\left(-1\right)}
Add 9 to -16.
k=\frac{-3±\sqrt{7}i}{2\left(-1\right)}
Take the square root of -7.
k=\frac{-3±\sqrt{7}i}{-2}
Multiply 2 times -1.
k=\frac{-3+\sqrt{7}i}{-2}
Now solve the equation k=\frac{-3±\sqrt{7}i}{-2} when ± is plus. Add -3 to i\sqrt{7}.
k=\frac{-\sqrt{7}i+3}{2}
Divide -3+i\sqrt{7} by -2.
k=\frac{-\sqrt{7}i-3}{-2}
Now solve the equation k=\frac{-3±\sqrt{7}i}{-2} when ± is minus. Subtract i\sqrt{7} from -3.
k=\frac{3+\sqrt{7}i}{2}
Divide -3-i\sqrt{7} by -2.
k=\frac{-\sqrt{7}i+3}{2} k=\frac{3+\sqrt{7}i}{2}
The equation is now solved.
\left(\sqrt{1^{2}+3-k}\right)^{2}=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Subtract 2 from 3 to get 1.
\left(\sqrt{1+3-k}\right)^{2}=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Calculate 1 to the power of 2 and get 1.
\left(\sqrt{4-k}\right)^{2}=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Add 1 and 3 to get 4.
4-k=\left(\sqrt{\left(4-2\right)^{2}+\left(2-k\right)^{2}}\right)^{2}
Calculate \sqrt{4-k} to the power of 2 and get 4-k.
4-k=\left(\sqrt{2^{2}+\left(2-k\right)^{2}}\right)^{2}
Subtract 2 from 4 to get 2.
4-k=\left(\sqrt{4+\left(2-k\right)^{2}}\right)^{2}
Calculate 2 to the power of 2 and get 4.
4-k=\left(\sqrt{4+4-4k+k^{2}}\right)^{2}
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(2-k\right)^{2}.
4-k=\left(\sqrt{8-4k+k^{2}}\right)^{2}
Add 4 and 4 to get 8.
4-k=8-4k+k^{2}
Calculate \sqrt{8-4k+k^{2}} to the power of 2 and get 8-4k+k^{2}.
4-k+4k=8+k^{2}
Add 4k to both sides.
4+3k=8+k^{2}
Combine -k and 4k to get 3k.
4+3k-k^{2}=8
Subtract k^{2} from both sides.
3k-k^{2}=8-4
Subtract 4 from both sides.
3k-k^{2}=4
Subtract 4 from 8 to get 4.
-k^{2}+3k=4
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{-k^{2}+3k}{-1}=\frac{4}{-1}
Divide both sides by -1.
k^{2}+\frac{3}{-1}k=\frac{4}{-1}
Dividing by -1 undoes the multiplication by -1.
k^{2}-3k=\frac{4}{-1}
Divide 3 by -1.
k^{2}-3k=-4
Divide 4 by -1.
k^{2}-3k+\left(-\frac{3}{2}\right)^{2}=-4+\left(-\frac{3}{2}\right)^{2}
Divide -3, the coefficient of the x term, by 2 to get -\frac{3}{2}. Then add the square of -\frac{3}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
k^{2}-3k+\frac{9}{4}=-4+\frac{9}{4}
Square -\frac{3}{2} by squaring both the numerator and the denominator of the fraction.
k^{2}-3k+\frac{9}{4}=-\frac{7}{4}
Add -4 to \frac{9}{4}.
\left(k-\frac{3}{2}\right)^{2}=-\frac{7}{4}
Factor k^{2}-3k+\frac{9}{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(k-\frac{3}{2}\right)^{2}}=\sqrt{-\frac{7}{4}}
Take the square root of both sides of the equation.
k-\frac{3}{2}=\frac{\sqrt{7}i}{2} k-\frac{3}{2}=-\frac{\sqrt{7}i}{2}
Simplify.
k=\frac{3+\sqrt{7}i}{2} k=\frac{-\sqrt{7}i+3}{2}
Add \frac{3}{2} to both sides of the equation.