Question

Trina has two brothers. one brother is 7 years older than trina and the other brother is 7 years younger than trina. the product of her brothers age is 95.

a. if x represents trinas age, write an equation to describe the product of her brothers ages.
b. solve the equation for x how old is trina.

Answer 1

(a) 95 = (x+7)*(x-7)

(b) 95 = (x+7)*(x-7)
Expand the brackets:
95 = x² -7x + 7x -49 = x² - 49
Subtract x² from both sides:
95-x² = -49
Subtract 95 from both sides:
-x²=-49-95
-x²= -144
Divide both sides by -1 to get rid of the negative numbers:
-x²/-1=-144/-1
x²=144
Take the square root of 144:
x = ± squareroot of 144
x = 12 or -12
x = 12 because you cannot have a negative age so Trina is 12 years old.