Question

решите неравенство 3^x+2 + 3^x+1 + 3^x < 39

Answer 1

3^x=t

9t+3t+t<39

13t<39

t<3

3^x<3

x<1

Answer 2

$3^{x+2}+3^{x+1}+3^x<39;\ 3^2*3^x+3^1*3^x+3^x<39;\ 9*3^x+3*3^x+3^x<39;\ (9+3+1)*3^x<39;\ 13*3^x<39;\ 3^x<frac{39}{13};\ 3^x<3;\ 3^x<3^1;\ 3>1;x<1;$

x є $(-infty;1)$