Question

The sum of 3 terms of G.P is 21/4 and their product is b common ratio is​

Answer 1

Answer:

let first three terms a/r ,a , ar

a/c to question,

sum of first three terms = 39/10

⇒a/r + a + ar = 39/10

⇒a[1/r + 1 + r] = 39/10 ........(1)

again, product of first three terms = 1

⇒a/r × a × ar = 1

⇒a³ = 1 = 1³

⇒a = 1 , putting in equation (1),

we get, 1[1/r + 1 + r] = 39/10

⇒(1 + r + r²)/r = 39/10

⇒10(1 + r + r²) = 39r

⇒10 + 10r + 10r² = 39r

⇒10r² - 29r + 10 = 0

⇒10r² - 25r - 4r + 10 = 0

⇒5r(2r - 5) - 2(2r - 5) = 0

⇒(5r - 2)(2r - 5) = 0

⇒r = 2/5 , 5/2

now, for a=1 and r = 2/5

three terms are ; 5/2, 1 , 2/5 

now , a= 1 and r= 5/2

three terms are ; 2/5,1,5/2

mark it as brainless

Answer 2

Answer:

ok

Step-by-step explanation:

its r = 4

hope u liked

follow