SOLUTION: {{{(x+1)(x+8)=-12}}}

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Question 77050This question is from textbook Glencoe Algebra 1
: This question is from textbook Glencoe Algebra 1

Found 2 solutions by jim_thompson5910, chitra:
Answer by jim_thompson5910(35256) (Show Source):
You can put this solution on YOUR website!

foil the left side
Add 12 to both sides

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 20 and add to 9? Lets find out by listing all of the possible factors of 20

Factors:

1,2,4,5,10,20,

-1,-2,-4,-5,-10,-20,List the negative factors as well. This will allow us to find all possible combinations

These factors pair up to multiply to 20.

1*20=20

2*10=20

4*5=20

(-1)*(-20)=20

(-2)*(-10)=20

(-4)*(-5)=20

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

Now which of these pairs add to 9? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 9

||||||
First Number | Second Number | Sum
1 | 20 | 1+20=21
2 | 10 | 2+10=12
4 | 5 | 4+5=9
-1 | -20 | -1+(-20)=-21
-2 | -10 | -2+(-10)=-12
-4 | -5 | -4+(-5)=-9
We can see from the table that 4 and 5 add to 9. So the two numbers that multiply to 20 and add to 9 are: 4 and 5 Now we substitute these numbers into a and b of the general equation of a product of linear factors which is: substitute a=4 and b=5 So the equation becomes: (x+4)(x+5) Notice that if we foil (x+4)(x+5) we get the quadratic again

So the quadratic factors to

Set each factor equal to zero

So our answer is
or
Answer by chitra(359) (Show Source):
You can put this solution on YOUR website!
The given expression is:

Multiplying the two term, this can be written as:

20 can be factored as 5 * 4

==> x + 5 = 0 OR x + 4 = 0

==> x = - 5 or x = -4

Hence, the solution.