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#