Math

QuestionRank the sums S30\mathrm{S}_{30} of these series from least to greatest: 4+15+26+4+15+26+\ldots, 77+79+81+77+79+81+\ldots, 12+17+22+12+17+22+\ldots, 178154130-178-154-130-\ldots.

Studdy Solution

STEP 1

Assumptions1. Each of the given series is an arithmetic series. . We need to find the sum of the first30 terms for each series, denoted as 30_{30}.
3. We need to rank these sums from least to greatest.

STEP 2

The sum of the first n terms of an arithmetic series can be calculated using the formulan=n2(a+l)_n = \frac{n}{2} (a + l)where nn is the number of terms, aa is the first term, and ll is the last term.

STEP 3

Since we are given that the series are arithmetic, the last term ll can be calculated using the formulal=a+(n1)dl = a + (n -1)dwhere dd is the common difference.

STEP 4

Calculate the common difference for the first seriesd=154=11d =15 -4 =11

STEP 5

Calculate the last term for the first seriesl=4+(301)×11=325l =4 + (30 -1) \times11 =325

STEP 6

Calculate 30_{30} for the first series30=302(4+325)=4945_{30} = \frac{30}{2} (4 +325) =4945

STEP 7

Repeat steps4 to6 for the second series. The common difference isd=7977=2d =79 -77 =2The last term isl=77+(301)×2=135l =77 + (30 -1) \times2 =135And 30_{30} is30=302(77+135)=3180_{30} = \frac{30}{2} (77 +135) =3180

STEP 8

Repeat steps4 to6 for the third series. The common difference isd=1712=5d =17 -12 =5The last term isl=12+(301)×5=157l =12 + (30 -1) \times5 =157And 30_{30} is30=302(12+157)=2535_{30} = \frac{30}{2} (12 +157) =2535

STEP 9

Repeat steps4 to6 for the fourth series. The common difference isd=154(178)=24d = -154 - (-178) =24The last term isl=178+(30)×24=494l = -178 + (30 -) \times24 =494And 30_{30} is30=302(178+494)=474_{30} = \frac{30}{2} (-178 +494) =474

STEP 10

Now that we have the sums for each series, we can rank them from least to greatest. The ranking is. 12+17+22+27+12+17+22+27+\ldots (30=2535_{30} =2535)
2. 77+79+81+83+77+79+81+83+\ldots (30=3180_{30} =3180)
3. 178154130106-178-154-130-106-\ldots (30=4740_{30} =4740)
4. 4+15+26+37+4+15+26+37+\ldots (30=4945_{30} =4945)

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