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Divide (2x^2 + 3x - 5) / (x - 1)

Step by step, with the reason for every step · Dividing polynomials · Algebra 2

Step by step

The question

Question: divide (2x² + 3x − 5) by (x − 1).

2x2 + 3x − 5x − 1

1 Set it up

We write it like long division with numbers.

x − 1 goes outside, 2x² + 3x − 5 inside.

2 First part of the answer

Divide the first parts: 2x² divided by x is 2x.

We write it on top.

Multiply: 2x times (x − 1) is 2x² − 2x.

We write it under, with a minus: we take it away.

2x² take away 2x² is 0.

That is why we chose 2x.

3x take away −2x is 5x.

Bring down the next part: −5.

3 Second part of the answer

Divide the first parts: 5x divided by x is 5.

We write it on top.

Multiply: 5 times (x − 1) is 5x − 5.

We write it under, with a minus: we take it away.

5x take away 5x is 0.

That is why we chose 5.

−5 take away −5 is 0.

The last part is 0.

So nothing is left over.

So the answer is 2x + 5.

Nothing is left over.

2x2 + 3x − 5x − 1 = 2x + 5

4 Check

Let's check with a number: x = 2.

First the start: 2x² + 3x − 5.

Start: 2(2)2 + 3(2) − 5 = 8 + 6 − 5 = 9

Now the answer: (x − 1) times (2x + 5).

Answer: (2 − 1) × (2(2) + 5) = (1) × (9) = 9

Both give 9.

So the answer is right!

Both give 9

Let's look back.

First: set it up.

Then: first part of the answer.

Then: second part of the answer.

Last: check.

Answer
2x2 + 3x − 5x − 1 = 2x + 5

Your turn

Try this one yourself, then check:

2x2 − 7x − 4x − 4
Show the answer
2x2 − 7x − 4x − 4 = 2x + 1

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