Question

Solve by factoring: X^2-3x-18=0

Answer 1

Answer:

x=6, -3

Step-by-step explanation:

Answer 2

Answer:

$x=-3\\x=6$

Step-by-step explanation:

We begin with $x^2-3x-18=0$

To factor this, we need to look for two things:

Two numbers that add together to get $-3$ and two numbers that multiply together to get $-18$.

One method to find the answer is to write out each of the solutions to the multiplication and then check the sum of each of those digits:

The numbers that multiply together to get $-18$ are:

1 and -18

-1 and 18

2 and -9

-2 and 9

3 and -6

-3 and 6

Now, we can add each of these pairs of digits together to find which one gives us an answer of $-3$

$1+(-18)=-17\\\\-1+18=17\\\\2+(-9)=-7\\\\-2+9=7\\\\3+(-6)=-3\\\\-3+6=3$

From this, we can see that 3 and -6 gave us the result of -3. This means that these are the two factors.

To get our answer from this, we need to put our answer in the form of $(x+a)(x+b)=0$

This gives us the factored form of $(x+3)(x-6)=0$

To solve this equation, we must make either parenthesis equal to zero. This means that our solutions will be

$x=-3\\x=6$