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?

Answer 1

If you use the quadratic equation, all you need to know are the first and last statement. The middle one can get confusing because you need to include absolute value. Set up a system of equations: {x+y=3.9 {x*Y=3.6 Solve the second one for x and you get x=3.6/y Substitute that for the x in the first equation and you get: (3.6/y) + y = 3.9 If you multiple the y by (y/y) you can change it to (y^2 / y) So the equation becomes: (3.6/y) + (y^2/y) = 3.9 Add like terms to get: (3.6 + y^2)/y = 3.9 Multiple both sides by y to get: 3.6 + y^2 = 3.9y Get all the terms one side and re-order them to make it look like a quadratic equation: y^2 -3.9y + 3.6 = 0 Now use a calculator program or the quadratic formula to solve. You get that the numbers are 2.4 and 1.5