How do you divide (3x3+12x2−21x−23)÷(x+5)?

1 Answer
IDKwhatName
Jul 5, 2017

3x2−3x−6 r 7

Explanation:

Firstly, you divide 3x3 by x to get 3x2. Then you do 3x2(x+5)=3x2+15x2.

3x3+12x2−3x3−15x2=−3x2, the first value of the quptient is 3x2.

Now you do −3x2x=−3x. Then you do −3x(x+5)=−3x2−15x.
(3x2−21x)−(−3x2−15x)=−21x+15x=−6x. −3x is the second part of the quotient.

Now you do −6xx=−6. Then you do −6(x+5)=−6x−30.
(−6x−23)−(−6x−30)=−23+30=7. −6 is the last part of the quotient. 7 is the remainder.

Visual guide:

3x2−3x−6 r 7
(x+5)/(3x3+12x2−21x−23)
−(3x3+15x2)
(0−3x2)
−(−3x2−15x)
(0−6x)
−(−6x−30)
(0+7)

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