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

Question

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

Answer 1

1;x<1;" alt="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;" align="absmiddle" class="latex-formula">

x є

Answer 2

3^x=t

9t+3t+t<39</p>

13t<39</p>

t<3</p>

3^x<3</p>

x<1</p>