Question

Find two numbers that have a product of -40 and a sum of 3.

Answer 1

8,- 5

Answer 2

let x ad y be the numbers

x + y = 3

xy = 40

let us use substitution

since x + y = 3

x = 3 - y

let us now substitute that to xy = 40

xy = 40

(3-y)y = 40

3y - y^2 = 40

put everything on the right side

y^2 - 3y + 40 = 0

you can factor this out into

(y+5)(y-8)

Answer 3

xy=-40
x+y=3

(x+y)^2=9
x^2+y^2+2xy=9
x^2+y^2+2(-40)=0
x^2+y^2-80=0
x^2+y^2=89

(x-y)^2 = x^2+y^2-2xy = 89 - 2(-40) = 89+80 = 169

(x-y)=+13 or -13

x-y = 13
x + y = 3

2x = 16 -2y=10
x=8 y=-5

Answer 4

thanks for simplifying that it really helped u guys :)

Answer 5

Or you can simply write out the factors of -40:
-10, 4 10,-4 8, -5 -8, 5 20, -2 -20, 2 and then testing which add up to 3

Answer 6

is there anyway i can give everyone a medal?

Answer 7

yes tell us to give a medal to which person i will give to other one..

Answer 8

okay well can @mathslover give one to @mashe then mashe give one to @lgbasallote

Answer 9

i gave

Answer 10

that's an unusual way to solve @mathslover nice ;)

Answer 11

thanks @lgbasallote

Answer 12

i gave my medal too early...