# Polynomial question

• September 12th 2011, 02:31 PM
jon80
Polynomial question
According to Edward T. Dowling within Schaum's Outline of Theory and problem of Mathematical methods for business and economics:

(3x^3 - 5x^2 y^2 - 2y^3)(7x-4y) = 21x^2 - 12x^y - 35x^3y^2 +20x^2y^3 - 14xy^3 + 8y^4

Can you clarify?

NOTE: Enclosing the above within is not readable through Latex.
• September 12th 2011, 02:39 PM
Quacky
Re: Polynomial question
Use the [TEX][ /TEX] tags, not the [tex][/MATH ] ones.

$(3x^3 - 5x^2 y^2 - 2y^3)(7x-4y)$

$=7x(3x^3 - 5x^2 y^2 - 2y^3)-4y(3x^3 - 5x^2 y^2 - 2y^3)$

$=7x(3x^3)+7x(-5x^2y^2)+7x(-2y^3)-4y(3x^3)-4y(-5x^2y^2)-4y(-2y^3)$

$=21x^4-35x^3y^2...$

Finish and simplify and see what you get.