Ineed find the sum of the first 42 terms of the sequences (12, 16, 20,
a) 3,717
b) 3,948
c) 1,134
d) 4,032

Answers

its b because u have to add them all up

56

Step-by-step explanation:

17,661

Step-by-step explanation:

-10, 2, 14, 26

T1 = a = -10

T2 = 2

T3 = 14

T4 = 26

Lets find the common difference

T2 - T1 = T3 - T2

2 - (-10) = 12 = 14 - 2 = 12

common difference d = 12

therefore, this is an arithmetic progression

Sum of first 42 terms

S42 = n/2 [2a + (n - 1) * d]

where n = 42

slot in the values

S42 = 42/2 [2*(-10) + (42 -1)* 12]

S42 = 21[ -20 + (41*12)]

S42 = 21 ( -20 + 861)

S42 = 21( 841)

S42 = 17,661

B

Step-by-step explanation:

Note the common difference between consecutive terms of the sequence.

d = 16 - 12 = 20 - 16 = 4

This indicates the sequence is arithmetic with sum to n terms

S_{n} = \frac{n}{2} [2a₁ + (n - 1)d ]

where a₁ is the first term and d the common difference

Here a₁ = 12 and d = 4, thus

S_{42} = \frac{42}{2} [ (2 × 12) + (41 × 4) ]

                          = 21( 24 + 164) = 21 × 188 = 3948 → B



Do you know the answer?

Other questions on the subject: Mathematics

answer: the answer is 30 miles per hour.ft/s -> mphmph = ft/s 1.466667mph = 44 divided by 1.466667mph = 30.00000- r3ktforgood ☕...Read More
1 more answers
Center: (-9, -2)Radius = 6Step-by-step explanation:The general equation of the circle is:The center of the circle is given as (-g, -f) and the radius of this circle is calculated a...Read More
2 more answers
Mathematics, 22.06.2019, laylay120
let x and 400 - x be the two numbers.   ==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.     < ==> 0.80x + 0.85(400 - x) = 400 - 6...Read More
3 more answers
Mathematics, 22.06.2019, sonyfan
$56,558.1Step-by-step explanation:This is a question on compound interest.The formula to calculate the Total Amount based on compound interest is given as:A = P( 1 + r/n) ^ntA = To...Read More
3 more answers