how do i factor b2 (squared) - 18b -144

2. Originally Posted by mathdummy232
how do i factor b2 (squared) - 18b -144
We need to find factors of -144 that add up to -18

lets check a few

$\displaystyle -12 \cdot 12=-144 \\\ -12+12=0$ nope

$\displaystyle -6 \cdot 24=-144 \\\ -6+24=18$

This is the right number but the wrong sign so we switch the minus sign

$\displaystyle 6 \cdot (-24)=-144 \\\ 6+(-24)=-18$

so Now if factors into

$\displaystyle (b+6)(b-24)$

3. ## Thanks so much

would you know how to do this equation too? It says subtract ( -2x+2) - (x2 (square) +x-3)

4. Originally Posted by mathdummy232
would you know how to do this equation too? It says subtract ( -2x+2) - (x2 (square) +x-3)
$\displaystyle (-2x+2)-(x^2+x-3)$

First we distribute the minus sign(or - is the same as -1), then collect the like terms

$\displaystyle -2x+2-x^2-x+3=-x^2-3x+5$

Good luck.

P.S. When you have an unrealated question it is okay to start a new thread

5. Originally Posted by mathdummy232
would you know how to do this equation too? It says subtract ( -2x+2) - (x2 (square) +x-3)
New questions need to go in new threads.

-Dan

6. \displaystyle \begin{aligned} b^{2}-18b-144&=\left( b^{2}-18b+81 \right)-144-81 \\ & =(b-9)^{2}-225=(b-9)^{2}-15^{2} \\ & =(b-9+15)(b-9-15) \\ & =(b+6)(b-24). \end{aligned}