Factor completely. x^2 – 3x – 18?

Question

please help

Answer 1

(x - 6) (x + 3)

Answer 2

ok
first step in factoring: put the terms in order from the highest exponent on the left to the lowest on the right

this is already done, so good.

2nd: look at the first term (x^2)
try to find 2 of the same numbers/variables that equal x^2 when multiplied by themselves
in this case, there is only 1 answer, which is x and x
(x*x=x^2)

3: now that you have the first term, set up your factoring space on your paper

(x + ?) * (x + ??) = x^2-3x-18

4: now, all you have is -3x-18
what you do is you find 2 numbers to fit the ?'s in the equation above so that:
?x+??x= -3
and ?*??= -18
5: first, list all the factors of -18, which are
1, -18
-1, 18
2, -9
-2, 9
3, -6
6, -3

then, you see which pair adds to equal -3
after plugging each one in, you see that -6 and 3 are the only ones that work
so you fill in the equation from step 3:

(x + 3) * (x - 6) = x^2 - 3x - 18

i did this lengthy explanation for you because it is REALLY important that you understand factoring

my friend didnt get it but we moved on to the next chapter
and factoring shows up EVERYWHERE
so just learn it once the first time
and it will get easier
and easier
and easier
hope this helps!

Answer 3

You've got a negative term at the end, which means you need one plus and one minus sign in your factors:
(x + ?)(x - ?)

Now you need to find two numbers whose product is 18 and difference is -3. The ones that work are 6 and 3. Put the 6 in front of the minus sign so that you wind up with -3 and not 3.
(x + 3)(x - 6)

Answer 4

Remember that to factor, you want to come up with factors of the C part (-18) that add together to give you the coefficient of the B part (-3x).

The answer is:
(x - 6)(x + 3)

Answer 5

(x - 6)(x + 3)

Answer 6

(x - 6)(x + 3)

Answer 7

(x-6)(x+3)

Answer 8

(x - 6)(x + 3)

To check, use the FOIL method:
Multiply the first, F, terms together:
x * x = x², so far so good
Now, multiply the outside, O, terms:
x * 3, or 3x
Now, multiply the inside, I, terms:
(-6) * x, or -6x
Now, multiply the last, L, terms:
(-6) * 3, or -18
Now, put them all together:
x² + 3x - 6x - 18
Combine like terms:
x² - 3x -18
Q.E.D.

Answer 9

(X-6)(X+3)