Factor:
d2 – 144

and please explain how you did it if that isn't too much?

Question

Factor:
d2 – 144

and please explain how you did it if that isn't too much?

whpalmer4 · Answer

Both d^2 and 144 are squares, so this is a difference of two squares.
$$(x-a)(x+a) = x^2 + ax - ax - a^2 = x^2-a^2$$

All you need to do is figure out what the square root of 144 is, and what the square root of d is, and then you have your factors.

$$(\sqrt{d^2} - \sqrt{144})(\sqrt{d^2} + \sqrt{144})$$

whpalmer4 · Answer

Sorry, "what the square root of $d^2$ is"

whpalmer4 · Answer

Learn to recognize this pattern, you'll use it often when factoring.

anonymous · Answer

So.. (d-12)(d+12)?

whpalmer4 · Answer

Correctamundo!

whpalmer4 · Answer

$$(d-12)(d+12) = d^2 -12d + 12d -144 = d^2 - 144$$

anonymous · Answer

Thank you so much!

whpalmer4 · Answer

You're welcome.  Like I said, keep your eyes open for other opportunities to use that trick!

directrix · Answer

Difference of Two Squares Study Aid