SOLUTION: What two numbers when added equals 7 but when multiplied equals -5

Algebra ->  Customizable Word Problem Solvers  -> Numbers -> SOLUTION: What two numbers when added equals 7 but when multiplied equals -5      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 1045482: What two numbers when added equals 7 but when multiplied equals -5
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
system%28x%2By=7%2Cxy=-5%29

y=7-x
-
x%287-x%29=-5
7x-x%5E2=-5
7x-x%5E2%2B5=0
-x%5E2%2B7x%2B5=0
x%5E2-7x-5=0

x=%287%2B-+sqrt%2849%2B4%2A5%29%29%2F2
highlight%28x=%287%2B-+sqrt%2869%29%29%2F2%29

xy=-5
y=-5%2Fx
y=-5%2F%28%287%2B-+sqrt%2869%29%29%2F2%29
highlight%28y=-10%2F%287%2B-+sqrt%2869%29%29%29

The plus form for the x goes with the plus-form for y;
the minus form for x goes with the minus-form for y;
and THEN simplify in each case, the expression for y, or to rationalize the denominator.