# Math Help - Factoring

1. ## Factoring

Factor 24w squared -71w-30 Please help me find an answer that makes sense I am definately stuck on this one.

2. $24w^2-71w-30=(3w-10)\cdot(8w+3)$
It's a Quadratic equation, so using the quadratic formula for solving the equation $24w^2-71w-30=0$: $w_{1,2}=\frac {71\pm\sqrt{71^2-4\cdot 24\cdot (-30)}}{2\cdot 24}$ which gives the solutions $\frac {10}3$ and $-\frac{3}{8}$.

3. Hello, jennifer_person!

Factor: . $24w^2 -71w-30$
What does that mean?
Surely, it's easier to say "find an answer that is correct"
. . (as opposed to several billion answers that are not correct).

Has anyone taught you the way to factor trinomials (in general)?

We have: . $24w^2 - 71w - 30$

Multiply the first coeffient by the last coefficient: . $24\cdot30 \:=\:720$

Note the sign of the last term.
. . If it is "plus", think "SUM".
. . If it is "minus", think "DIFFERENCE".

The last term is -30, so we think "difference."

Factor 720 into two parts whose difference is the middle coefficient, 71.

How do we find that pair?
Start dividing 720 by 1, 2, 3, 4, etc., keeping the ones that "come out even."

$720 \;=\;\begin{array}{cc}1\cdot720 \\ 2\cdot360 \\ 3\cdot240 \\ 4\cdot180 \\ 5\cdot144 \\ 6\cdot120 \\ 8\cdot90 \\ 9\cdot 80 & \Leftarrow \text{ Here! a difference of 71}\end{array}$

The pair we want is: (9, 80).

Since the middle term is -71, we will use: +9 and -80
We use these numbers as coefficients for the "middle term".

We have: . $24w^2+ 9x - 80w - 30$

Factor in pairs: . $3w\underbrace{(8w+3)} - 10\underbrace{(8w + 3)}$
. . . . . . . . . . . . . . . . . $^{\text{common factor}}$

Factor: . $(8w+3)(3w-10)$ . . . There!