The nth term of a sequence is n^2 + 20.

Mathematics

1 answer:

Olegator [25]3 years ago

3 0

Answer:

$\large\boxed{a)\ 21,\ 24,\ 29}\\\boxed{b)\ \text{five terms}}$

Step-by-step explanation:

$a_n=n^2+20\\\\a)\\\\\text{Substitute}\ n=1,\ n=2\ \text{and}\ n=3\ \text{to the }\ a_n:\\\\a_1=1^2+20=1+20=21\\\\a_2=2^2+20=4+20=24\\\\a_3=3^2+20=9+20=29$

$b)\\\\\text{You have to solve the inequality:}\\\\n^2+20$

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Russell has a collection of 1,200 pennies. Of these pennies, 25% are dated before 1980, 35% are dated from 1980 to 2000, and the

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480 pennies.

25% are dated before 1980, therefore:
1200(total):100 = 12 (1%)
12(1%)x25 = 300 (25%)

35% are dated from 1980 to 2000, therefore:
12(1%)x35 = 420 (35%)

25% are dated before 1980, 35% are dated from 1980 to 2000 and the rest are dated after 2000.
25% + 35% = 60%.
300(25%) + 420(35%) = 720.
60% = 720.
100%-60% = 40%.
40% is the amount of pennies that are dated after 2000.

The total (100%) of the pennies is 1200.
We also know that 60% of the total (1200) is 720.

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Therefore, the amount of pennies dated after 2000 in Russell’s Collection is 480.

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3 years ago

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Answer:

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Step-by-step explanation:

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Area of both triangles:

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