Question

(9 la puterea x+2) + (9 la puterea x+1) + (9 la x) = 91 ori 3 la puterea 28
Cat e x?

Answer 1

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