Question

in a gp a1 = 20, a4= 540 then r=?

Answer 1

Answer:

Step-by-step explanation:

The general term of G.P is $a_n= a\:{r}^{n-1}$

$a_1=20\\a=20$

$a_4=540\\\\a\:{r}^3=540$

${r}^3=\frac{540}{a}\\\\{r}^3=\frac{540}{20}\\\\{r}^3=27\\\\r=3$

Answer 2

HELLO DEAR,





given, a1 = 20 = a, a4 = 540

The general term of G.P is a_n= arⁿ-¹

so, a4 = 540 = ar³


=> r³ = 540/20

=> r³ = 27

=> r = 3


hence, r = 3




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THANKS