PSAT Math : How to multiply polynomials

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : How To Multiply Polynomials

F(x) = x^{3} + x^{2} - x + 2 

and

G(x) = x^{2} + 5  

What is ?

Possible Answers:

(FG)(x) = x^{5} + x^{4} - x - 2

(FG)(x) = x^{3} + 2x^{2} - x + 7

(FG)(x) = x^{5} + x^{4} +4x^{3} + 7x^{2} - 5x +10

(FG)(x) = x^{5} + x^{4} - x^{3} + 2x^{2} - 5x -10

(FG)(x) = x^{3} - x - 3

Correct answer:

(FG)(x) = x^{5} + x^{4} +4x^{3} + 7x^{2} - 5x +10

Explanation:

(FG)(x) = F(x)G(x) so we multiply the two function to get the answer.  We use x^{m}x^{n} = x^{m+n}

Example Question #1 : Multiplying And Dividing Polynomials

Multiply:

Possible Answers:

Correct answer:

Explanation:

This product fits the sum of cubes pattern, where :

So

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