SOLUTION: Rosalyn is 7 years older than chris. In 5 years' time the product of their ages will be 588. find chris and rosalyn's ages now.
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-> SOLUTION: Rosalyn is 7 years older than chris. In 5 years' time the product of their ages will be 588. find chris and rosalyn's ages now.
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You can put this solution on YOUR website! let r = R's age
let c = C's age
;
write an equation for each statement
:
Rosalyn is 7 years older than chris.
r = c + 7
:
In 5 years' time the product of their ages will be 588.
(r+5)(c+5) = 588
replace r with (c+7)
(c+7 + 5)(c+5) = 588
(c+12)(c+5) = 588
FOIL
c^2 + 5c + 12c + 60 - 588 = 0
c^2 + 17c - 528 = 0
You can us the quadratic formula, but this will factor to
(c+33)(c-16) = 0
the positive solution is all we want here
c = 16 yr is C's age
then
16 + 7 = 23 yrs is R's age
:
:
See if that checks out, in five years time:
21 * 28 = 588
