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2 votes
Find the product mentally.

(ab + 3)(ab - 3)

A: a2b2 + 9
B: a2b2 - 6ab - 9
C: a2b2 - 9

User Jblejder
by
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2 Answers

3 votes
(ab+3)(ab−3)

=(ab+3)(ab+−3)

=(ab)(ab)+(ab)(−3)+(3)(ab)+(3)(−3)

=a^2b^2−3ab+3ab−9

=a^2b^2−9

User Jason LiLy
by
7.2k points
5 votes

Answer:

Option (c) is correct.


\left(ab\:+\:3\right)\left(ab\:-\:3\right)=a^2b^2-9

Explanation:

Given :
\left(ab\:+\:3\right)\left(ab\:-\:3\right)

We have to find the product of
\left(ab\:+\:3\right)\left(ab\:-\:3\right)

Consider the given expression
\left(ab\:+\:3\right)\left(ab\:-\:3\right)

Apply algebraic identity,
\left(a+b\right)\left(a-b\right)=a^2-b^2

We have,

a = ab and b = 3


=\left(ab\right)^2-3^2

Simplify, we have,


=a^2b^2-9

Thus,
\left(ab\:+\:3\right)\left(ab\:-\:3\right)=a^2b^2-9

User Ezer
by
8.2k points

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