6th grade math
posted by Alex on .
Can you check #18 and explain how to do #15 please?
15. Sue ordered 4 pizzas for 6 dollars each and 2 twelve packs of coke for x amount. Use the distributive property to create an equivalent expression.
Ans: not sureseems like they're not related.
6*4=2(12x)
24 =2(12 + x)
18. One person in my class will call 3 people, and each of those people will contact 3 other people, and so on. How many people will be contacted in the 5th round? Write your answer in exponent form and find the value.
Ans: 3^5 = 243

4*6 + 2x
or
2(6+x)
consider that at each round, if there are x people already contacted, then 3x more will be contacted, making for a total of 4x after the round. So, the sequence looks like this:
1
1+3 = 4
4+12 = 16
16+48 = 64
...
Round n: 4^(n1) + 3*4^(n1) = 4^n
So, for round 5, there are already 4^4 = 256 people, and 3*256 = 768 more will be contacted, totaling 4^5 = 1024 at the end of round 5.