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Solve for x (complex solution)
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x^{2}=-49
Subtract 49 from both sides. Anything subtracted from zero gives its negation.
x=7i x=-7i
The equation is now solved.
x^{2}+49=0
Quadratic equations like this one, with an x^{2} term but no x term, can still be solved using the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}, once they are put in standard form: ax^{2}+bx+c=0.
x=\frac{0±\sqrt{0^{2}-4\times 49}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and 49 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\times 49}}{2}
Square 0.
x=\frac{0±\sqrt{-196}}{2}
Multiply -4 times 49.
x=\frac{0±14i}{2}
Take the square root of -196.
x=7i
Now solve the equation x=\frac{0±14i}{2} when ± is plus.
x=-7i
Now solve the equation x=\frac{0±14i}{2} when ± is minus.
x=7i x=-7i
The equation is now solved.