SOLUTION: Karen is 5 years older than Sean. The product of their ages is 300. How old is Karen?

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Question 842605: Karen is 5 years older than Sean. The product of their ages is 300. How old is Karen?
Answer by thejackal(72) About Me  (Show Source):
You can put this solution on YOUR website!
if karens age is x, and we know that karen is seans age + 5 lets form an equation.
let seans age be y such that y + 5 = x
if y * (y + 5) = 300 find the value of x
solve for y first
y^2 + 5y = 300
we now have a quadratic equation
y^2 + 5y - 300 = 0
You can solve it using any of the known methods: perhaps the easiest here would be the quadratic formula.
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a = 1; b = +5; c = -300
the result will be the roots -20 and 15; since age can't be less than 0 we can discard the first root.
so seans age is 15 and therefore karens age is 15+5 = 20 years