How do you multiply (4x + 3) ( 5x - 2) ?

2 Answers
Jun 23, 2017

20x^2+7x-6

Explanation:

(color(blue)(4x)color(darkred)(+3))(color(red)(5x)color(green)(-2))

You proceed to FOIL it:

Where you multiply the color(blue)"first term" with the color(red)"outer term" then you multiply the color(blue)"first term" with the color(green)"inner term":

(color(blue)(4x))(color(red)(5x))=20x^2

(color(blue)(4x))(color(green)(-2))=-8x

Now you multiply the color(darkred)"last term" with the color(red)"outer term" then you multiply the color(darkred)"last term" with the color(green)"inner term":

color(darkred)((3))(color(red)(5x))=15x

color(darkred)((3))(color(green)(-2))=-6

Now combine them:

20x^2-8x+15x-6

Simplify:

20x^2+7x-6

Jun 23, 2017

You would have to FOIL it up.
To be exact it is F^2O^2I^2L^2 or square foil.
FirstXFirst; OuterXOuter; InnerXInner; LastXLast.

Explanation:

We will use this example: (4x+3)(5x-2)to using square foil

FXF: 4x xx 5x= 20 x^2

OXO: 4x xx -2 = -8x

IXI: 3 xx 5x = 15x

LXL: 3 xx -2 = -6

Then re-assembling: (4x+3)(5x-2) = 20x^2 -8x+15x-6

(4x+3)(5x-2) = 20x^2 +7x-6