How to do the problem (7-2√3)(7+2√3)

Do you FOIL this or something? I thought the answer was like 37 or something... The radical problems are very confusing to me :(

Please help!

Multiply every number in first () with every in other () and you get:
49 + 14√3 - 14√3 - 12 - + 14√3 and -14√3 cancel each other and you have ( you got it right )

The last multiplication:
(-2√3)(2√3) =
(-2*2)(√3*√3)= -4(3) = -12

Example:
(-2√4)(2√4) = (-2 * 2)(2*2) = -4(4) = -16

right

and my way:
(-2√4)(2√4) = (-2*2)(√4 *√4) = -4(4) = -16


You got it man?

YOu get it