
Jane C. answered 03/07/16
Tutor
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Let x = 1st number
2x + 2 = the other number
Their product is 40. So, (2x + 2)x = 40
Multiply (2x + 2) and x and get 2x2 + 2x = 40
2x2 + 2x - 40 = 0
Factor it out. The factors are (2x + 10) and (x - 4).
(2x + 10) (x - 4) = 0
Find the roots.
a) 2x = -10
x = -10/2 = -5
Solve the other number using x = -5
2x + 2
2(-5) + 2 = -10 + 2 = -8
Then the first pair of numbers is (-5,-8)
b) x - 4 = 0
x = 4
Solve the other number using x = 4
2x + 2
2(4) + 2 = 8 + 2 = 10
x = 4
Solve the other number using x = 4
2x + 2
2(4) + 2 = 8 + 2 = 10
Then the second pair of numbers is (4,10)