Factor the expression below. x^2-64
a. (x+8)(x-8)
b. (x-8)(x-8)
c. (x+16)(x-4)
d. (x-16)(x-4)

At a point on the ground 50 meters from the foot of a tree, the angle of elevation to the tree is 48°. find the height of the tree to the nearest meter.

Sam opened a money-market account that pays 3% simple interest. he started the account with $7,000 and made no further deposits. when he closed the account, he had earned $420 in interest. how long did he keep his account open?

What is perpendicular to y=-1/2x+11