How do you multiply (8x + 3) ( 8x - 3)(8x+3)(8x3)?

2 Answers
Nov 21, 2016

64x^2-964x29

Explanation:

F.O.I.L

First, Outer, Inner, Last

Multiply the First terms in each set of parenthesis

8x xx8x=64x^28x×8x=64x2

Multiply the Outermost terms in each set of parenthesis

8x xx -3=-24x8x×3=24x

Multiply the Inner most terms in each set of parenthesis

3 xx 8x=24x3×8x=24x

Multiply the Last terms in each set or parenthesis

3xx-3=-93×3=9

64x^2-24x+24x-964x224x+24x9

Combine like terms

64x^2-964x29

This is DTS, or Difference of Two Squares

Because the first term, 6464, can be square rooted and the last term, 99, can be square rooted

Nov 21, 2016

(8x+3)(8x-3)=64x^2-9(8x+3)(8x3)=64x29

Explanation:

(8x+3)(8x-3)(8x+3)(8x3)

This is an example of a difference of squares: (a^2-b^2)=(a+b)(a-b)(a2b2)=(a+b)(ab), where a=8xa=8x and b=3b=3.

(8x)^2-(3^2)(8x)2(32)

64x^2-964x29

You could also use the FOIL method, though it is more work. However, you should know both procedures in case your instructor indicates a specific method.

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(8x+3)(8x-3)=8x*8x+8x*-3+3*8x+3*-3(8x+3)(8x3)=8x8x+8x3+38x+33

(8x+3)(8x-3)=64x^2-24x+24x-9(8x+3)(8x3)=64x224x+24x9

(8x+3)(8x-3)=64x^2-cancel(24x)+cancel(24x)-9

(8x+3)(8x-3)=64x^2-9