How do you factor $x^{2} + 3 x - 18 = 0$ $x^2 +3x - 18 = 0$ ?

Question

How do you factor $x^{2} + 3 x - 18 = 0$ $x^2 +3x - 18 = 0$ ?

1 Answer

Impact of this question

11514 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-05-23T09:20:52

$x^{2} + 3 x - 18$ $x^2 + 3x -18$

We can Split the Middle Term of this expression to factorise it.

In this technique, if we have to factorise an expression like $a x^{2} + b x + c$ $ax^2 + bx + c$ , we need to think of 2 numbers such that:

$N_{1} \cdot N_{2} = a \cdot c = 1 \cdot (- 18) = - 18$ $N_1*N_2 = a*c = 1*(-18) = -18$
and,
$N_{1} + N_{2} = b = 3$ $N_1 +N_2 = b = 3$

After trying out a few numbers we get $N_{1} = 6$ $N_1 = 6$ and $N_{2} = - 3$ $N_2 =-3$
$6 \cdot (- 3) = - 18$ $6*(-3) = -18$ and $6 + (- 3) = 3$ $6+(-3)= 3$

$x^{2} + 3 x - 18 = x^{2} + 6 x - 3 x - 18$ $x^2 + 3x -18 = x^2 + 6x - 3x -18$

$x (x + 6) - 3 (x + 6)$ $x(x+6) -3(x+6)$

$(x - 3) (x + 6)$ $color(green)((x-3)color(red)((x + 6)$ is the factorised form.

Science

Math

Humanities

... and beyond

How do you factor $x^{2} + 3 x - 18 = 0$ $x^2 +3x - 18 = 0$ ?

1 Answer

Related questions

Impact of this question

Science

Math

Humanities

... and beyond

How do you factor x2+3x−18=0x^2 +3x - 18 = 0?

1 Answer

Related questions

Impact of this question

How do you factor $x^{2} + 3 x - 18 = 0$ $x^2 +3x - 18 = 0$ ?