Test:75 QNo:7

4th term of an AP equals 2 times the 1st term. Fifth term is greater than 2 times the 4th term by 5. The 19th term is?

3 Answers

1
bharish94 ·

isn't d= -1?

1
Abhisek ·

a + 3d = 2a
or, a=3d

(a+4d) - 2(a+3d) = 5
or, -a-2d=5
or, -5d=5 [since, a=3d]
or, d= -1

so a= 3d = -3.

t19 = -3 + (19-1)(-1) = -21.

1
suprit sahu ·

it should be d=-1 and a=-3

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