Question

Part A: The area of a square is (4a2 − 20a + 25) square units. Determine the length of each side of the square by factoring the area expression completely. Show your work. (5 points) Part B: The area of a rectangle is (9a2 − 16b2) square units. Determine the dimensions of the rectangle by factoring the area expression completely. Show your work. (5 points)

Answer 1

Answer:

• (2a -5)²
• (3a -4b)(3a +4b)

Step-by-step explanation:

There are a couple of factored forms that are used here:

  (a +b)² = a² +2ab +b² . . . . the sign of "2ab" will match the sign of b

  a² -b² = (a -b)(a +b)

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Part A:

 Since this trinomial is known to be a perfect square, you can find the binomial(s) by looking at the roots of the first and last terms.

  √(4a²) = 2a

  √25 = 5

The factoring is ...

  4a² -20a +25 = (2a -5)²

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Part B:

This is the difference of perfect squares, so the terms of the factors can be found as in the previous part.

  √(9a²) = 3a

  √(16b²) = 4b

Using the above factored form, we have ...

  9a² -16b² = (3a -4b)(3a +4b)