math
posted by kate on .
the sum of two decimal numbers is 3.9. their difference is 0.9, and their poduct is 3.6 what are these two numbers?

The problem is overdefined, namely there are three conditions, but only two unknowns. It is possible that we don't have a solution if the conditions do not agree. We'll see.
Use the first two conditions to solve for x, y such that x+y=3.9, xy=0.9, which gives x=2.4, y=1.5.
Now, multiply 2.4 by 1.5. If the product is 3.6, the solution is fine, if not, the problem is inconsistent.
Can you decide to which case the problem belongs?