arithmetic progression
posted by oladepo .
the 9th term of an AP is 52 while the 12th term is 70. find the sum of it's 20th term?

arithmetic progression 
Reiny
9th term = 52 > a + 8d = 52
12th term = 70 > a + 11d = 70
subtract them
3d = 18
d = 6
then a+48 = 52
a = 4
20th term = a + 19d = 4 + 114 = 118 
arithmetic progression 
Suraj
118

arithmetic progression 
HASSAM
118

arithmetic progression 
Anonymous
9th term = 52
a+8d=52
12th term = 70
a+11d =70
Subtract them
a+8d=52

a+11d =70
3d=18
d=6 buy dividing both side by 3
To fine a
a+8d=52
When d= 6
a+8(6)=52
a+48=52
a=5248
a=4
Then the sum of 20th term
Will be
S20= n/2[2a + (n1)d]
S20= 20/2[2(4) + (201)6]
S20=10[8+19(6)]
S20=10[8+114]
S20=10[122]
S20=1220 answer 
arithmetic progression 
Taiwo
9th term = 52
a+8d=52
12th term = 70
a+11d =70
Subtract them
a+8d=52

a+11d =70
3d=18
d=6 buy dividing both side by 3
To fine a
a+8d=52
When d= 6
a+8(6)=52
a+48=52
a=5248
a=4
Then the sum of 20th term
Will be
S20= n/2[2a + (n1)d]
S20= 20/2[2(4) + (201)6]
S20=10[8+19(6)]
S20=10[8+114]
S20=10[122]
S20=1220 answer 
arithmetic progression 
Taiwo
Since is sum of 20th term not the 20th term then the answer is 1220
Respond to this Question
Similar Questions

Maths
1) In the arithmetic progression, the 8th term is twice the 4th term and the 20th term is 40. Find the common difference and the sum of the terms from the 8th to the 20th term inclusive. 2) Find the least number of terms of the AP, … 
arithmetic
The 9th term of an A.p is 32 while the12th termis70.find the sum of it 20th term 
math
the 9th term of an AP is 52 while the 12th term is 70.find the sum of its 20th term 
math
d 9th term of an Ap is 52 while d 12th term is 70. find sum of it's 20th term? 
math
pls help me out in dis ? dat says The 9th term of an Ap is 52 while d 12th term is 70 find d sum of it's 20th term? 
arithmetic
Determining the first three terms of an ArithmetiC progressionof which the (a.)10th term is 31 and the 15th term is 49 (b.)7th term is 3 and 12th term is 3 (c.)5th term is 8 and the 11th term is 28 (d.)9th term is7+9x and d=2x,Show … 
math
The 3rd term of an Arithmetic Progression is 10 more than the first term while the fifth term is 15 more than the second term. Find the sum of the 8th and 15th terms of the Arithmetic Progression if the 7th term is seven times the … 
Maths
The 5th term of an arithmetic progression is 3times of 2nd term and 12th term exceeds 2times of 6th term by 1. Find the 16th term 
Maths
The 5th term of an arithmetic progression is 3times of 2nd term and 12th term exceeds 2times of 6th term by 1. Find the 16th term 
Maths
The 5th term of an arithmetic progression is 3times of 2nd term and 12th term exceeds 2times of 6th term by 1. Find the 16th term