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Explanation:

we know, the area of a rectangle is

length × width

so, we have here

length × (x - 5) = x² - 7x + 10

therefore,

length = (x² - 7x + 10) / (x - 5)

so, just by looking at it (with experience) I see that length is (x - 2).

but let's do the actual polynomial division, which seems to be the desired exercise here.

x² - 7x + 10 ÷ x - 5 =

it is very similar to actual number divisions.

we go from left to right.

we start with the first term (x²) and see how many times (x - 5) would fit into it. for that we look only at the first term in x - 5 (that is x).

x² / x = x

that is already our first term of the result (quotient) :

x² - 7x + 10 ÷ x - 5 = x

now, we multiply that result with the divisor (x - 5) and subtract that from the dividend.

x² - 7x + 10 ÷ x - 5 = x

- x² - 5x

--------------

0 - 2x

and now we pull down the next term from the dividend :

x² - 7x + 10 ÷ x - 5 = x

- x² - 5x

--------------

0 - 2x + 10

and we repeat the process with that new dividend :

-2x / x = -2

that is our next term of the quotient.

x² - 7x + 10 ÷ x - 5 = x - 2

- x² - 5x

--------------

0 - 2x + 10

we repeat the process of multiplying that term (-2) with the divisor (x - 5) and subtracting that result from the dividend :

x² - 7x + 10 ÷ x - 5 = x - 2

- x² - 5x

--------------

0 - 2x + 10

- -2x + 10

-------------

0 0

there is no remainder, and there is no more term to pull down. we are finished.

the result of the division is (as expected) : x - 2

the expression to describe the length is therefore

x - 2

User Galupuf
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