Question

plz solve this ques its urgent​

Answer 1

Answer:

Option(D)

Step-by-step explanation:

(i) Difference between the 4th term and 1st term is 52:

⇒ ar³ - a = 52

⇒ a(r³ - 1) = 52.

(ii) Sum of its first three terms is  26.

⇒ a + ar + ar² = 26

⇒ a(1 + r + r²) = 26.

On solving (i) & (ii), we get

⇒ (r³ - 1)/(1 + r + r²) = 52/26

⇒ (r - 1)(1 + r + r²)/(1 + r + r²) = 2

⇒ r - 1 = 2

⇒ r = 3

Substitute r = 3 in (i), we get

⇒ a(r³ - 1) = 52

⇒ a(27 - 1) = 52

⇒ a = 2.

Sum of the first six terms:

= a(r⁶ - 1)/r - 1

= 2(3⁶ - 1)/3 - 1

= 2(728)/2

= 728.

∴ Sum of first 6 terms is 728.

Hope it helps!