#### Anna Barkley

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- Thread starter Anna Barkley
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Please share your work for part (a). Did you derive the equation shown? Please share work.I'm a bit confused when it comes to number 3.

Is 3 a) supposed to be (x-7) (x+10)?

Also, I'm thinking that b's solution is the answer to (x-7) (x+10).

Help is greatly appreciated, thank you!

View attachment 26231

What did you mean by:

".....b's solution is the answer to (x-7) (x+10)"

Can you restate it another way? "(x-7) (x+10)" is a statement - does not have an "

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You're getting things out of order.I'm a bit confused when it comes to number 3.

Is 3 a) supposed to be (x-7) (x+10)?

Also, I'm thinking that b's solution is the answer to (x-7) (x+10).

Help is greatly appreciated, thank you!

View attachment 26231

The way to answer (a) is to show why, if the mean of x numbers is x-3, and their sum is 70, then x^2 - 3x - 70 = 0. To do that, write an expression for the sum of the numbers if there are x of them and their mean is x-3, and set that equal to 70. This will not involve the factors you wrote.

Then, one way to answer (b) is to factor the equation from (a), which turns out to be

Assign letters to the numbers you do not know.

\(\displaystyle \text {Let } x = \text {the number of numbers, and }\\

y = \text {mean of the numbers.}\)

Two unknowns requires two equations.

You are told that

\(\displaystyle y = x - 3.\) And

\(\displaystyle y = \dfrac{70}{x}.\) WHY?

Now solve.