The answer depends on how the terms and defined.
Suppose the first term is a, the second is a+r and the nth is a+(n-1)r. Then the sum of the first five = 5a + 10r = 85 and the sum of the first six = 6a + 15r = 123 Solving these simultaneous equations, a = 3 and r = 7 So the first four terms are: 3, 10, 17 and 24
(Sum of terms)/(number of terms) (10+10+10+2)/4=8
2
Sum of 1st 2 terms, A2 = 2 + 4 = 6 Sum of 1st 3 terms, A3 = 2 + 4 + 6 = 12 Sum of 1st 4 terms A4 = 2 + 4 + 6 + 12 = 20 you can create a formula for the sum of the 1st n terms of this sequence Sum of 1st n terms of this sequence = n2 + n so the sum of the first 48 terms of the sequence is 482 + 48 = 2352
The sum of the first 10 even numbers is 110.
Suppose the first term is a, the second is a+r and the nth is a+(n-1)r. Then the sum of the first five = 5a + 10r = 85 and the sum of the first six = 6a + 15r = 123 Solving these simultaneous equations, a = 3 and r = 7 So the first four terms are: 3, 10, 17 and 24
-8
-69
(Sum of terms)/(number of terms) (10+10+10+2)/4=8
The sum of 10*1 is 10.
We need the common difference to accurately get the first term and then use it to find the sum of the first 20 terms.
The sum of the first 10 multiples of 3 is 165.
Calculating an average is done in two steps: - First: you calculate the sum of the terms whose average you would like to calculate. - Second: you divide the sum of the terms by their number. In your case: - First: 10 + 6 + 12 = 28 - Second: 28 / 3 = 9.33333.... 3 is the number of terms added together which are: 10, 6 and 12 (3 numbers). Answer: Therefore your average is: 9.33333....
2
The sum of the 1st n terms is : N(3N-1)/2 Explanation : The sum from 1 to N of (3m-2) = 3 * sumFrom1toN(m) - sumFrom1toN(2) = 3 * (N*(N+1)/2) -2*N = N(3N-1)/2 For N=10 => 145
Sum of 1st 2 terms, A2 = 2 + 4 = 6 Sum of 1st 3 terms, A3 = 2 + 4 + 6 = 12 Sum of 1st 4 terms A4 = 2 + 4 + 6 + 12 = 20 you can create a formula for the sum of the 1st n terms of this sequence Sum of 1st n terms of this sequence = n2 + n so the sum of the first 48 terms of the sequence is 482 + 48 = 2352
Factor as : (x+9)(x+10) using the first terms ( x terms) multiply to x2; the last terms multiply to 90; the sum of 9x + 10 x = 19x