Asked by oladepo

the 9th term of an AP is 52 while the 12th term is 70. find the sum of it's 20th term?
Answered by 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
Answered by Suraj
118
Answered by 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=52-48
a=4
Then the sum of 20th term
Will be
S20= n/2[2a + (n-1)d]
S20= 20/2[2(4) + (20-1)6]
S20=10[8+19(6)]
S20=10[8+114]
S20=10[122]
S20=1220 answer
Answered by Taiwo
Since is sum of 20th term not the 20th term then the answer is 1220
Answered by Oluwatobi
Gud subject maths
Answered by Iheanacho john
I love Osinachi
Answered by James
Not a correct answer
Answered by Pascal chukwuemeka
The 9th and 12th terms of an AP are 50 and 65 respectively.find (a) the common difference (b) the sum of it's first 70 terms
Answered by John
Since


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