Answer:
8 days
Step-by-step explanation:
On day 8, Isabella will save 256 nickels, bringing her total to 510.
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The number of nickels saved on day n is 2^n. The total is 2^(n+1)-2.
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The above can be written down from your knowledge of binary sequences. If you want a more formal development, read on.
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The number of nickels saved on day n is a geometric sequence with first term 2 and common ratio 2. The n-th term of the sequence is ...
an = a1·r^(n-1) = 2·2^(n-1) = 2^n
The sum of n terms of the sequence is ...
S = a1(r^n -1)/(r -1) = 2(2^n -1)/(2-1)
S = 2^(n+1) -2
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We want S > 500, so ...
500 < 2^(n+1) -2
502 < 2^(n+1)
251 < 2^n
log(251) < n·log(2)
n > log(251)/log(2)
n > 7.97 . . . . . . . . 8 days or more to save more than 500 nickels
Answer:
y to 0.78y is a decrease
Step-by-step explanation:
y by itself can also be written as 1y, and 0.78y is less than 1, thus y to 0.78y is a decrease.
Step 3:
5x + 20 + 3x + 9x + 7 becomes
5x + 3x + 9x + 20 + 7
Step 4:
(5x + 3x + 9x) + (20 + 7)
Step 5:
17x + 27
If you have any further questions feel free to ask.
Hope this helps
Answer:
y=4/5x + 2
Step-by-step explanation:
y=mx+b
find slope which is 8/10=4/5
choose a y and plug into problem
I uploaded the answer to a file hosting. Here's link:
tinyurl.com/wpazsebu
