Question

Multiply and simplify: (3x – 7)(3x + 7)

A. 9x2 – 42x – 49
B. 9x2 – 42x + 49
C. 9x2 + 49
D. 9x2 – 49

Answer 1

\( \color{Black}{\Rightarrow 3x(3x + 7) - 7(3x + 7)}\)

Answer 2

Use:

\[(a-b)(a+b) = a^2 - b^2\]

Answer 3

^ which is the Difference of Perfect Squares rule.

Answer 4

Well you can use either methods

Answer 5

Using Difference of Perfect Square you get:
9x^2-49
Therefore, answer is D.

Answer 6

i have a simple formula\[(a+b)\times(a-b) =a ^{2} -b ^{2}\]

Answer 7

so we get answer
\[9x ^{2}-49\]