Question

7. Is 6x4 - 13x3 + 8x2 + 11x + 12 is a factor of 2x + 3.
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Answer 1

Answer:

Simplify (x3 + 3x2 + 5x – 4) – (3x3 – 8x2 – 5x + 6)

The first thing I have to do is take that "minus" sign through the parentheses containing the second polynomial. Some students find it helpful to put a "1" in front of the parentheses, to help them keep track of the minus sign.

Here's what the subtraction looks like, when working horizontally:

(x3 + 3x2 + 5x – 4) – (3x3 – 8x2 – 5x + 6)

(x3 + 3x2 + 5x – 4) – 1(3x3 – 8x2 – 5x + 6)

(x3 + 3x2 + 5x – 4) – 1(3x3) – 1 (–8x2) – 1(–5x) – 1(6)

x3 + 3x2 + 5x – 4 – 3x3 + 8x2 + 5x – 6

x3 – 3x3 + 3x2 + 8x2 + 5x + 5x – 4 – 6

–2x3 + 11x2 + 10x –10