SOLUTION: Hello. I am having troubles with the problem -x^2-7x+30. Factoring trinomials. Write each factor in descending order. I'm not getting an answer, I don't know what would multiply to

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Question 472326: Hello. I am having troubles with the problem -x^2-7x+30. Factoring trinomials. Write each factor in descending order. I'm not getting an answer, I don't know what would multiply to 30 and add to 7.
Found 2 solutions by ewatrrr, MathLover1:
Answer by ewatrrr(24785) (Show Source):
You can put this solution on YOUR website!

Hi,
-x^2-7x+30
factoring
(-x + 3)(x + 10)
Checking the factoring using FOIL
F First terms -x^2
O Outside terms -10x
I Inside terms 3x
L Last terms 30

Answer by MathLover1(20850) (Show Source):
You can put this solution on YOUR website!

Solved by pluggable solver: Factoring Quadratics with a leading coefficient of 1 (a=1)

In order to factor , first we need to ask ourselves: What two numbers multiply to 30 and add to -7? Lets find out by listing all of the possible factors of 30

Factors:

1,2,3,5,6,10,15,30,

-1,-2,-3,-5,-6,-10,-15,-30,List the negative factors as well. This will allow us to find all possible combinations

These factors pair up to multiply to 30.

1*30=30

2*15=30

3*10=30

5*6=30

(-1)*(-30)=30

(-2)*(-15)=30

(-3)*(-10)=30

(-5)*(-6)=30

note: remember two negative numbers multiplied together make a positive number

Now which of these pairs add to -7? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -7

||||||||
First Number | Second Number | Sum
1 | 30 | 1+30=31
2 | 15 | 2+15=17
3 | 10 | 3+10=13
5 | 6 | 5+6=11
-1 | -30 | -1+(-30)=-31
-2 | -15 | -2+(-15)=-17
-3 | -10 | -3+(-10)=-13
-5 | -6 | -5+(-6)=-11
None of these factors add to -7. So this quadratic cannot be factored. In order to solve for x, we need to use the quadratic formula.