a) $3^{x+2}$ `+` `3^x` `=270`
→ `3^x` . `3^2` `+` `3^x` `=270`
→ `3^x` . (`3^2` `+1)` `=270`
→ `3^x` . `10=270`
→ `3^x` `=270:10`
→ `3^x` `=27`
→ `3^x=3^3`
→ `x=3`
b) `(x^2` `-29)^3` `=` `343`
→ `(x^2` `-29)^3` `=` `7^3`
→ `x^2` `-29=7`
→ `x^2` `=7+29`
→ `x^2` `=36`
→ `x^2=6^2`
→ `x=6`