Question 238282
Notes:
* When we multiply a variable to another term that has the same variable, we multiply their coefficients, but add their exponents.
* In this case, {{{x}}} would be the same as to say {{{1x^1}}} 
* And {{{3x}}} would be the same as to say {{{3x^1}}}
* When 1 is the coefficient and/or the exponent, we don't write down.  It is known to be understood or implicit.
* So now multiply the coefficients and add the exponents

x(3x) = (1x^1)*(3x^1} = 3x^2