How do you do the following problem?
the sum of two decimal numbers is 3.9. their difference is 0.9 and their product is 3.6. What are the two numbers?
the sum of two decimal numbers is 3.9. their difference is 0.9 and their product is 3.6. What are the two numbers?
Michael B
Favorite Answer
x + y = 3.9
x * y = 3.6
x * (3.9 - x) = 3.6
3.9x - x^2 = 3.6
x^2 - 3.9x +3.6 = 0
using quadratic formula
x = (3.9 + or - sqrt(3.9^2 - 4(3.6)))/2
x = 1.5 or 2.4
There are two possible solutions:
x is 1.5 y is 2.4
x is 2.4 y is 1.5
Anonymous
x + y = 3.9
x - y = 0.9
2y = 4.8
y = 2.4
x + 2.4 = 3.9
x = 1.5
so the two numbers are 2.4 and 1.5
to prove is 2.4 x 1.5 = 3.6