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If this is for factoring, here’s how to do it.

7. 45n^2-5

-first, ask yourself what common factor does 45n^2 and 5 have? The answer is that they’re both divisible by 5

-next you want to expand this expression by dividing 5 out and rewriting it in multiplication. If you completely remove the 5 from the expression, you have created a new and different expression (which is not the goal). And so you will have:  5(9n^2-1)

-now we have to expand 9n^2-1. We know that (a-b)(a+b)=a^2-b^2; once you foil and multiply the expression, you’ll notice you cancelled ab with ab. So for this problem, you need to see what will make 9 and 1 once you square them(It’s 3 and 1).

-what you should have now is 5(3n-1)(3n+1). But ways check by foiling your answer to see if you end up with the same expression.

9. 45a^3-80a

what is similar about 45a^3 and 80a?

- both divisible by 5a

5a(9a^2-16)

what do you square to get 9 and 16

- 3 and 4

5a(3a-4)(3a+4)

When it comes to bigger numbers, use the quadratic formula to find the variables that‘ll be part of your factored answers(Remember to apply the opposite sign/operation when you insert the numbers you got from the formula - because the numbers from the formula are the solutions ex. If I got 3 and -4 from the formula, my factored expression would be (X-3)(X+4))

(-1,-0.5)

step-by-step explanation:

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm