Solve for x (complex solution)
x=-\frac{3}{4}i=-0.75i
x=\frac{3}{4}i=0.75i
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16x^{2}=-9
Subtract 9 from both sides. Anything subtracted from zero gives its negation.
x^{2}=-\frac{9}{16}
Divide both sides by 16.
x=\frac{3}{4}i x=-\frac{3}{4}i
The equation is now solved.
16x^{2}+9=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 16\times 9}}{2\times 16}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 16 for a, 0 for b, and 9 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\times 16\times 9}}{2\times 16}
Square 0.
x=\frac{0±\sqrt{-64\times 9}}{2\times 16}
Multiply -4 times 16.
x=\frac{0±\sqrt{-576}}{2\times 16}
Multiply -64 times 9.
x=\frac{0±24i}{2\times 16}
Take the square root of -576.
x=\frac{0±24i}{32}
Multiply 2 times 16.
x=\frac{3}{4}i
Now solve the equation x=\frac{0±24i}{32} when ± is plus.
x=-\frac{3}{4}i
Now solve the equation x=\frac{0±24i}{32} when ± is minus.
x=\frac{3}{4}i x=-\frac{3}{4}i
The equation is now solved.
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