Question

The 4th term of a G.P. is square of its second term,and the first term is -3. Find its 7th term.

Answer 1

Hi!

The first term, a of the G.P. is given as –3.

The n^th term of the G.P. is given by a_n = ar^{n – 1}

∴Second term, a₂ = ar = –3r

4^th term, a₄ = ar³ = –3r³

It is given that, –3r³ = (–3r)²

∴–3r³ = 9r²

⇒ r = –3

Thus, 7^th term, a₇ = ar⁶ = –3(–3)⁶ = –2187

Hope! You got the answer.

Cheers!