Question

multiplication of Polynomial 3x × 4x2=?
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Answer 1

Answer:

Simplify (x + 2)(x3 + 3x2 + 4x – 17). I'm just going to do this one vertically; horizontally is too much trouble.

Answer 2

Here's what the multiplication looks like when it's done horizontally:

(4x2 – 4x – 7)(x + 3)

(4x2 – 4x – 7)(x) + (4x2 – 4x – 7)(3)

4x2(x) – 4x(x) – 7(x) + 4x2(3) – 4x(3) – 7(3)

4x3 – 4x2 – 7x + 12x2 – 12x – 21

4x3 – 4x2 + 12x2 – 7x – 12x – 21

4x3 + 8x2 – 19x – 21

That was painful! Now I'll do it vertically:



That was a lot easier! But, by either method, the answer is the same:

4x3 + 8x2 – 19x – 21