Posted by Benjamin on .
Given that 1st term of an A.P is 7 and it's 10th term is twice the second term,calculate the (a) 19th term (b)sum of 28 terms (c) difference between 9th and 6th terms

Math? 
Writeacher,
Statistics??
What's the SUBJECT?? 
Community technical college 
bobpursley,
a10=a1+r(101)
14=7+r(9)
r=7/9
check
7, 7 7/9, 7 14/9, 7 21/9, 7 28/9, 7 35/9, 7 42/9, 7 49/9, 7 56/9, 14
Use the formulas for sum, knowing r, a1 
King george memorial college (Ilado Badagry Lagos state) 
Michael Samuel,
1st term=7 2nd term=a+d
10term=a+9d
7+9d=2(14+2d)
147=9d2d
7=7d=d=1
sum of 28 term
n/2(2a+(n1)d)
28/2(2*7+(281)1)
14(14+27)=14(41)
25term=574
9th term=7+(91)1
7+(91)
7+8=15
6th term=7+(61)1
7+(61)=7+5=12
9th term6th term=1512=3.