Question

(3^x-1)+(3^x+1)=90,, find x​
insert formulas while writing for easy understanding.

Answer 1

||✪✪ QUESTION ✪✪||

if 3^(x-1) + 3^(x+1) = 90,, find x ?

|| ✰✰ ANSWER ✰✰ ||

we have ,

3^(x-1) + 3^(x+1) = 90

Solving it by using a^m * a^n = a^(m+n)

→ [ 3^x * 3^(-1) ] + [ 3^x * 3^1 ] = 90

Now , using a^(-b) = 1/a^b

→ [3^x * 1/3 ] + [3^x * 3 ] = 90

Taking 3^x common now, we get,

→ 3^x [ 1/3 + 3 ] = 90

→ 3^x [ (1+9)/3 ] = 90

→ 3^x (10/3) = 90

→ 3^x = 90*3/10

→ 3^x = 27

→ 3^x = 3³

Comparing now, we get, (As , base are same) .

→ x = 3.

Hence, value of X is 3.

Answer 2

Answer:

(3x-1) (3x+1)=90

by using (a-b) (a+b)= a^2 -b^2

(3x)^2 -(1)^2