Question

( T ) What is the sum of the multiples of 6 between 8 and 70?

( E ) What is the sum of the multiples of 5 between 12 and 92?

( A ) What is the sum of the multiples of 3 between 1 and 50?

( F ) What is the sum of the multiples of 11 between 10 and 122?

( B ) What is the sum of the multiples of 9 between 25 and 100?

( U )What is the sum of the first 20 terms of the arithmetic sequence with first term 3 and common difference 3?

( H ) What is the sum of the first 15 terms of the arithmetic sequence with first term - 4 and common difference 4?

( N ) What is the sum of the first 32 terms of the arithmetic sequence with first term 5 and common difference - 6?

( K ) What is the sum of the first 27 terms of the arithmetic sequence with first term 8 and common difference -2?

( L ) What is the sum of the first 51 terms of the arithmetic sequence with first term - 7 and common difference 2?

CHOICES TO COMPLETE WORD'S:

567 840 390 360 408 -2816 -486 726 630 2193​

Answer 1

Answer:

(T) 390

(E) 840

(A) 408

Step-by-step explanation:

(T) multiples of 6 between 8 and 70

12, 18, 24, . . . , 66

a = 12, d = 6, and tn = 66.

tn = a+(n-1)d

66 = 12+(n-1)6

54 = (n-1)6

n-1 = 54/6 = 9

n = 10.

Now,

Sn = n/2.[a+tn]

Sum = 10/2.[12+66] = 5x78 = 390.

(E) multiples of 5 between 12 and 92

15, 20, 25, . . . , 90

a = 15, d = 5, and tn = 90.

.tn = a+(n-1)d

90 = 15+(n-1)5

75 = (n-1)5

n-1 = 75/5 = 15

n = 16.

.Now,

.Now,Sn = n/2.[a+tn]

.Now,Sn = n/2.[a+tn]Sum = 16/2.[15+90] = 8x105 = 840.

(A) multiples of 3 between 1 and 50

3, 6, 9, 12, . . . , 48

a = 3, d = 3, and tn = 48.

.tn = a+(n-1)d

48 = 3+(n-1)3

45 = (n-1)3

n-1 = 45/3 = 15

n = 16.

.Now,

.Now,Sn = n/2.[a+tn]

.Now,Sn = n/2.[a+tn]Sum = 16/2.[3+48] = 8x51 = 408.