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The area of a rectangle knitted blanket is 9x^2-6x-8. What are the possible dimensions of the blanket? Use factoring ​

User Drhodes
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1 Answer

11 votes

Answer:

(3x-4) by (3x+2) or (-3x+4) by (-3x-2)

Explanation:

To factor 9x^2-6x-8 we want to find the factors of 9 and the factors of -8 that when multiplied in sequence and then added give us -6.

factors of -8:

-8 & 1

8 & -1

-4 & 2

4 & -2

you might also want to remember that these can be flipped, so if you have -8 & 1 you can also have 1 &-8.

factors of 9:

9 & 1

-9 & -1

3 & 3

-3 & -3

So now we just need to find numbers where

a & b are factors of 9 and c & d are factors of -8 and a*c+b*d=-6,

if that is the case then (ax+c)*(bx+d)=9x^2-6x-8

guess: 3 & 3 and -4 & 2

3*(-4) + 3*2=-12 +6 = -6

so one factoring is (3x-4)*(3x+2)

This means that one of the possible dimensions of the blanket is (3x-4) by (3x+2)

guess: -3 & -3 and 4 & -2

(-3)*4+(-3)*(-2)= -12+6 = -6

so another factoring is (-3x+4)*(-3x-2)

So you could also have a blanket with dimensions (-3x+4) by (-3x-2) but this might not make sense to do because, if you input positive numbers for x you will get negative dimensions which in the real world don't exist for a knitted blanket.

p.s sorry for the late response.

User Marshall Conover
by
8.1k points
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