Question

(27^-x+3)(9^x+1)=81 what is answer?

Answer 1

(27⁽⁻ˣ⁺³⁾) (9⁽ˣ⁺¹⁾) = 81

Instead of using logarithmic to find x, Notice that 27, 9 and 81 are the perfect powers of 3. Since 27 = 3³, 9 = 3², and 81 = 3⁴, so

(3³⁽⁻ˣ⁺³⁾) (3²⁽ˣ⁺¹⁾) = 3⁴
3³⁽⁻ˣ⁺³⁾⁺²⁽ˣ⁺¹⁾ = 3⁴

If the bases are the same, then cancel it and bring the power as a new base.
3(-x+3) + 2(x+1) = 4
-3x + 9 + 2x + 2 = 4
-x + 11 = 4
-x = 4 - 11
-x = -7
x = 7