what do u multiply to get 30, but add to get -13? Has to be the same 2 #s.?

Answer 1

If this isn't an algebra question and the method doesn't matter, this is solved easier and faster using "guess and check". You know they must be factors of 30 and must both be negative. Try all possible combinations. There aren't that many.

Answer 2

Since multiplied they create a positive number, yet add up to a negative number, they both have to be negative. A positive multiplied by a negative always creates a negative number, where as like multiples always create positives. Secondly, they both have to be factors of -30, obviously, that add up to -13.

Choices would be(forget the negative for a moment):

1, 30 = 31
2, 15 = 17
3, 10 = 13

Answer is -3, -10

Answer 3

1) x*y = 30
2) x+y = -13

modifying 1) into
y = 30/x

inserting 1) into 2) gives

x + (30/x) = -13
(30/x) = -13 - x
30 = -13x - x^2
0 = -13x - x^2 -30
13x + x^2 + 30 = 0

factoring we get (x+3)*(x+10) = 0
meaning the possible answers are -3,-10 for x

placing these possible answers into equation 1 for x to get y we get

x + y = -13 placing -3 in we have:

-3 + y = -13
y = -10

so one answer is (-3, -10)

trying the other number we have:

-10 + y = -13
y = -3

so the other answer is (-10, -3)
since these are the SAME sets of numbers (but in opposite orders of presentation) the two numbers are -10 and -3

this is solving simultaneous equations.
to know if you can solve the set of problems you must have as many equations as there are variables your looking to solve and allways be sure to check the sets of answers (especially with polynomial or non contuinues equations)

Answer 4

The two numbers are -3 and -10.

(-3) x (-10) = 30


(-3) + (-10) = -13

Answer 5

xy = 30, and x + y = -13. Rearrange the second equation to look like this: x = -13 - y. Substitute this value into the first equation, so it looks like this: (-13 - y)y = 30. Multiply on the left side (-13y - y^2 = 30). Rearrange this: y^2 + 13y + 30 = 0. Solve as a quadratic equation.

Answer 6

-3 and -10

Answer 7

-3,-10

Answer 8

-3, -10