what is the correct answer of (3a+b)(-2a-4b) using foil method

Expert Answers
samhouston eNotes educator| Certified Educator

FOIL stands for First, Outside, Inside, Last.  It is an algorithm used for multiplying binomials.

(3a + b)(-2a - 4b)

Product of the First terms:  3a * -2a = -6a^2

Product of the Outside terms:  3a * -4b = -12ab

Product of the Inside terms:  b * -2a = -2ab

Product of the Last terms:  b * -4b = -4b^2

-6a^2 + -12ab + -2ab + -4b^2

Add like terms.

-6a^2 + -14ab + -4b^2


-6a^2 - 14ab - 4b^2



justaguide eNotes educator| Certified Educator

We have to determine the result of (3a+b)(-2a-4b).

Using FOIL, first multiply the first terms, or 3a and -2a, then multiply the outer terms or 3a and -4b, then multiply the inner terms b and -2a and finally multiply the last terms b and -4b.


=> 3a*(-2a) + 3a*(-4b) + b*(-2a) + b*(-4b)

=> -6a^2 - 12ab - 2ab - 4b^2

=> -6a^2 - 14ab - 4b^2

The result of (3a+b)(-2a-4b) = -6a^2 - 14ab - 4b^2

givingiswinning | Student

FOIL mean First Outer Inner Last


Think of this as:

`3a*(-2a) + 3a*(-4b) + b*(-2a) + b*(-4b)`

`-6a^2 - 12ab - 2ab - 4b^2`

Combine terms, this leaves:

`-6a^2 - 14ab - 4b^2`

taangerine | Student



  • Rewrite  (3a+b)(-2a-4b)
  • Use Foil (3a)(-2a)+(3a)(-4b)+(-2a)(b)+(b)(-4b)
  • Simplify `-6a^(2)-12ab-2ab-4b^(2)`
  • Combine like terms: `-6a^(2)-14ab-4b^(2)`
crystaltu001 | Student


Distribute the 3a to the -2a and -4b and you will get -6a^2-12ab

Then you distribute the b to the -2a and -4b and you will get -2ab - 4b^2

and then you combine like terms and you will get

-6a^2 - 4b^2 - 14ab

lwong9706 | Student

-6a^2 - 14ab - 4b^2

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