posted by Lily
Find the two numbers that multiply to the product number and add to the sum number of the following:
a)Product 563033256; Sum 51895
b)Product -43481220; Sum 28429
c)Product 2545124358; Sum -105619
I tried xy = product and x+y = sum, but it didn't work out... Can someone please help me?
x+y = sum --->
y = sum - x
product = xy = x(sum-x) ------>
x^2 - sum x + product = 0
x = sum/2 ± sqrt[(sum/2)^2 - product]
There are two solutions because interchanging x and y in the solution will yield another solution. This means that you can take:
x = sum/2 - sqrt[(sum/2)^2 - product]
y = sum/2 + sqrt[(sum/2)^2 - product]
sorry, but I don't get it; how can I have two different solutiuons hen I'm only supposed to have one? Still, thanks.
If you have a solution and you interchange x and y then the sum and the poduct are the same, so that's another solution. This means that when we solve for x we get two solutions, the other solution bwing the value for y.
oh, okay, I get it now; thanks!