Answers:
- <u>24000 dollars</u> invested at 4%
- <u>18000 dollars</u> was invested at 7%
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Work Shown:
x = amount invested at 4%
If she invests x dollars at 4%, then the rest (42000-x) must be invested at the other rate of 7%
She earns 0.04x dollars from that first account and 0.07(42000-x) dollars from the second account
This means we have
0.04x+0.07(42000-x)
0.04x+0.07*42000-0.07x
0.04x+2940-0.07x
-0.03x+2940
This represents the total amount of money earned after 1 year.
We're told the amount earned in interest is $2220, so we can say,
-0.03x+2940 = 2220
-0.03x = 2220-2940
-0.03x = -720
x = -720/(-0.03)
x = 24000 dollars is the amount invested at 4%
42000-x = 42000-24000 = 18000 dollars was invested at 7%
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As a check, we can see that
18000+24000 = 42000
and also
0.04x = 0.04*24000 = 960 earned from the first account
0.07*18000 = 1260 earned from the second account
1260+960 = 2220 is the total interest earned from both accounts combined
This confirms our answers.
1)
n 1 2 3 4 5 6
f(n) 1033 932 831 730 629 528
First term (a₁): <u>1033 </u> Common difference (d): <u>-101 </u>
Explicit rule:
Recursive rule: 




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2)
n 1 2 3 4 5 6
f(n) -39 -29 -19 -9 9 19
First term (a₁): <u> -39 </u> Common difference (d): <u> +10 </u>
Explicit rule:
Recursive rule: 




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3)
n 1 2 3 4 5 6
f(n) 3.75 2.5 1.25 0 -1.25 -2.5
First term (a₁): <u> 3.75 </u> Common difference (d): <u> -1.25 </u>
Explicit rule:
Recursive rule: 




Answer:C or 11
Step-by-step explanation:
3x²-1
First you insert x... which is 2
3(2)²-1
then you square the 2. (multiply it by itself)
3(4)-1
Then you multiply 3 by 4 to get 12
12-1
And then you subtract for your answer
11