Use the expression 8a + 16c. part a factor the expression using the gcf. a. 2(4a + 8c) b. 4(2a + 4c) c. 8(a + 2c) d. 16(12a + c) part b what is the value of the expression when a = –5 and c = –1? enter your answer in the box.

Part A.

C. 8 (a + 2c)

Explanation:
The answer is c because when you have this equation (below) you have find what both numbers are divisible by:



Both of these numbers are divisible by 8 (This number would be on the outside of the parenthesis).



Now that you know they're both divisible by 8 you can start to put together your equation. So far you should have this:

8 (? +?)

Now to find the other numbers you have to think... what number multiplied by 8 will make it equal to 8a? The answer would be a. 8 times a = 8a. (Another way to do this is to just divide 8a by 8 same with 16)

Now your equation should look like this:

8 (a + ?)

Now do the same thing with the 16c as you did with the 8a. (either divide 16c by 8 or think of a number times 8 that will make it equal 16c) For this one I'm going to use the division method - so what is 16c ÷ 8? 16 ÷ 8 = 2 and finally just add the c. So your answer is 2c.

Your equation should not look like this:

8 (a + 2c)

You're done!

Part B.

-56

Eplanation:
To find this just plug in the numbers into the equation. a = -5 and c = -1.
For this I used the original equation :



Plug in the numbers....



And solve!



And finally....



So the value of the equation if a were -5 and c were -1 would be -56!