Question

Determinati valoarea lui x, stiind ca 9 la puterea x+2 + 9 la puterea x+ 1 + 9 la puterea x = 91 × 3 la puterea 28
Ajutorrr

Answer 1

9laxx9²+9laxx9+9lax=91x3la28
9lax(81+9+1)=91x3la28
91x9lax=91x3la28÷91
9lax=3la28
(3²)x=3la28
3la2x=3la28
2x=28
x=14

Answer 2

$9^{x+2} + 9^{x+1} + 9^{x}=91* 3^{28} \\ 9^{x} ( 9^{2} + 9 + 1)=91* 9^{14} \\ 9^{x}*91=91* 9^{14} => 9^{x}= 9^{14} => x=14$
Solutie:x=14.