2007-04-04 17:36:22 · 10 answers · asked by Anonymous in Education & Reference ➔ Homework Help
-15 and +2
2007-04-04 17:39:37 · answer #1 · answered by craigcougar64 2 · 0⤊ 0⤋
alright, for this, you have to create some variables. Let X and Y be the 2 numbers.
so you know that X*Y = -30 and X+Y = 13.
rearrange the first equation by dividing both sides by X, so you get Y = -30/X
Put this value of Y into the second equation:
X + (-30/X) = 13,
multiply both sides by X to get rid of the fraction:
X^2 - 30 = 13X..........bring everything to the left
X^2 - 13X - 30 = 0..........solve the quadratic equation
you could either look for 2 numbers that add to -13 and multiply to -30 (but that is what the question asks for, so if you could do that, then you wouldn't need to do this. so use the quadratic equation:
X = [13 +- sqrt (13^2 - 4(1)(-30))] / 2
X = [ 13 +- sqrt 289] / 2
X = (13 +- 17) / 2
X = 30/2 and -4/2
X = 15 and -2
once you have this value of X, put it into any of the 2 equations you have above:
X*Y = -30
(15) * Y = -30
Y = -30/15 = -2
X*Y = -30
(-2) * Y = -30
Y = -30/-2 = 15
X + Y = 13
(15) + Y = 13
Y = -2
-2 + Y = 13
Y = 15
So you get the same values no matter which X you use in the equations. So the 2 numbers are 15 and -2.
Hope that helped you
2007-04-05 00:45:02 · answer #2 · answered by Anonymous · 1⤊ 0⤋
-2 and 15
2007-04-05 01:11:40 · answer #3 · answered by Dave aka Spider Monkey 7 · 0⤊ 0⤋
-15 & +2
2007-04-05 00:48:30 · answer #4 · answered by Christian Mata 2 · 0⤊ 0⤋
15, -2
2007-04-05 00:39:40 · answer #5 · answered by jholcomb 3 · 0⤊ 0⤋
first set up two equations representing the two unknowns.
It should look something like this:
(x)(y)= -30
x+y =13
here x and y repressent the two unknown #'s.
next solve both equations for y (or x):
-30x^-1=y
-x+13=y
next solve simultaneously to get two sets of solutions:
(or plug equation 1 into equation 2 or vice versa)--and solve
first soln:
x= -2 and y=15
or
x= 15 and y= -2
If you have a TI-83 plug both equations into the calculator (the ones set equal to y) then sove graphically by finding the intersection of the two curves. hope this helps....
2007-04-05 01:09:53 · answer #6 · answered by rominger 1 · 0⤊ 0⤋
15 and -2 because:
15*-2= -30
15+-2=13
2007-04-05 00:48:43 · answer #7 · answered by sunshineangel 3 · 0⤊ 0⤋
it's either -15 and +2 or +15 and -2. could go either way
2007-04-05 00:43:46 · answer #8 · answered by cmeilinli 3 · 0⤊ 0⤋
15 and -2
to solve these, list the factors of the big number. Then play with them and the negative signs.
2007-04-05 00:39:54 · answer #9 · answered by msmthtchr 3 · 0⤊ 0⤋
Or you can turn them into equations
xy=-30
x+y=13
2007-04-05 00:42:33 · answer #10 · answered by Stina B 3 · 0⤊ 0⤋