Q. \(x^2 + 16 = 0\)

Answer

We solve \(x^2+16=0\).

\(x^2=-16\), so \(x=\pm 4i\).

Final result: \(x=4i\) or \(x=-4i\).

Detailed Explanation

We want to solve the equation

\[
x^2+16=0
\]

Step 1: Isolate the \(x^2\) term.

Subtract \(16\) from both sides so that the \(x^2\) term is alone on one side.

\[
x^2+16-16=0-16
\]

This simplifies to

\[
x^2=-16
\]

Step 2: Take the square root of both sides.

From \(x^2=-16\), we know \(x\) must be imaginary because the right-hand side is negative.

\[
x=\pm\sqrt{-16}
\]

Step 3: Rewrite \(\sqrt{-16}\) using \(i\).

We use the fact that \(i=\sqrt{-1}\). Then

\[
\sqrt{-16}=\sqrt{16\cdot(-1)}=\sqrt{16}\sqrt{-1}=4i
\]

So the solutions are

\[
x=\pm 4i
\]

Final Answer.

\[
\boxed{x=4i \text{ or } x=-4i}
\]

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Algebra FAQ

What are the solutions to \(x^2+16=0\)?

Solve \(x^2=-16\), so \(x=\pm 4i\).

How do you isolate \(x^2\) in \(x^2+16=0\)?

Subtract \(16\): \(x^2=-16\).

Why are the solutions complex?

Because \(x^2=-16\) is negative, and squares of real numbers cannot be negative, so \(x\) must be imaginary.

What is the square root of \(-16\)?

\(\sqrt{-16}=4i\) (principal square root). Thus the other root is \(-4i\).

How do you rewrite the equation using factoring?

It factors as \(x^2+16=(x-4i)(x+4i)=0\), giving \(x=4i\) or \(x=-4i\).

What if I use the quadratic formula on \(x^2+16=0\)?

With \(a=1,b=0,c=16\): \(x=\frac{-0\pm\sqrt{0-64}}{2}=\pm\frac{\sqrt{-64}}{2}=\pm 4i\).
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