Posted by **Benjamin** on Sunday, February 3, 2013 at 9:16am.

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**, Sunday, February 3, 2013 at 9:17am
Statistics??

What's the SUBJECT??

- Community technical college -
**bobpursley**, Sunday, February 3, 2013 at 10:58am
a10=a1+r(10-1)

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**, Sunday, October 11, 2015 at 3:35pm
1st term=7 2nd term=a+d

10term=a+9d

7+9d=2(14+2d)

14-7=9d-2d

7=7d=d=1

sum of 28 term

n/2(2a+(n-1)d)

28/2(2*7+(28-1)1)

14(14+27)=14(41)

25term=574

9th term=7+(9-1)1

7+(9-1)

7+8=15

6th term=7+(6-1)1

7+(6-1)=7+5=12

9th term-6th term=15-12=3.

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