Question

use the FOIL method to solve:
(3x-4)(3x+4)

Answer 1

\(\begin{align}
\text{F.O.I.L. = First Outside Inside Last}\\
\hline \\
&(ax+b)(cx+d)\\ \ \\
\text{First:}&(\color{blue}{ax}+b)(\color{blue}{cx}+d)\to \color{blue}{ax}\cdot\color{blue}{cx}=\color{blue}{acx^2}\\
\text{Outside:}&(\color{green}{ax}+b)(cx+\color{green}{d})\to \color{green}{ax}\cdot\color{green}{d}=\color{green}{adx}\\
\text{Inside:}&(ax+\color{red}{b})(\color{red}{cx}+d)\to \color{red}{b}\cdot\color{red}{cx}=\color{red}{bcx}\\
\text{Last:}&(ax+\color{orange}{b})(cx+\color{orange}{d})\to \color{orange}{b}\cdot\color{orange}{d}=\color{orange}{bd}\\
\hline \\
(ax+b)(cx+d)&=\color{blue}{acx^2}+\color{green}{adx}+\color{red}{bcx}+\color{orange}{bd}
\end{align}\)

Answer 2

i just needed it actually solved

Answer 3

Eww my LaTeX was hard work

Answer 4

jk it's @nbouscal 's work :)

Answer 5

\( \color{Black}{\Rightarrow (3x - 4)(3x + 4) }\)

\( \color{Black}{\Rightarrow (3x \cdot 3x) + (3x \cdot 4) + (-4 \cdot 3x) + (-4
\cdot 4) }\)

Answer 6

9x+12x-12x-16?

Answer 7

Yeah 9x^2 is the first term

Answer 8

And combine like terms

Answer 9

ok now when i simplify it even more what is it because wouldnt the two like terms (-12 and 12) cancel each other out

Answer 10

Yeah

Answer 11

so itd be 9x^2-16?

Answer 12

Yep

Answer 13

yay correct :) thanks