How do you evaluate (- 2x ^ { 3} + 5x ^ { 2} - 3x + 19) \div ( - x ^ { 2} - 4)(2x3+5x23x+19)÷(x24)?

1 Answer
Oct 21, 2017

-2x^3 + 5x^2 - 3x + 192x3+5x23x+19 = (-x^2-4x24) (2x-52x5) + 5x - 15x1

Explanation:

You have to use long division.
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NOTE:
-2x^3 + 5x^2 - 3x + 192x3+5x23x+19 = Dividend
-x^2-4x24 = Divisor
2x-52x5 = Quotient
5x - 15x1 = Remainder

Step 1:

  • You take the first value, -2x^32x3 and divide it by -x^2x2 which gives you 2x2x
  • Then to get the -2x^22x2 in the first line, you have to multiply the quotient, 2x2x by the divisor which is -x^2-4x24

That will give you -2x^3 - 8x 2x38x, the reason there's an empty space under 5x^25x2 is because there's no value in the divisor you can multiply the quotient by to get a x^2, so you leave the space BLANK, and bring it down to the next line

Step 2:

  • You have to imagine there's a subtract sign on the side, so you SUBTRACT the top by the bottom, -2x^22x2 - -2x^22x2 = 0
  • Then you would bring down 19, giving you 5x^2 + 5x + 195x2+5x+19
  • Now, you take ONLY the first value, 5x^25x2 and divide that by the divisor again, and you take that value and bring it up to the top.

Step 3:

  • Then multiply ONLY the value you got from dividing, 5, by the divisor once again. You would do, -5 *5-x^2x2, put it under 5x^25x2.

  • Then do -5 *5-4 which gives you 20, and put it under 19.

WHY PUT 20 UNDER 19?
Because you put values that have similar variables together, or in this case, constants with constants.

Stetp 4:
- Subtract like usual, and bring down the 5x5x since it was basically, 5x5x - 0x which equals, 5x5x

Answer:
(−2x3+5x2−3x+19)÷(−x2−4)(2x3+5x23x+19)÷(x24) = 2x - 52x5
and since it has a remainder you would include it as well giving you,
-2x^3 + 5x^2 - 3x + 192x3+5x23x+19 = (-x^2-4x24) (2x-52x5) + 5x - 15x1