Answer
$7x^{2}+28x$
Work Step by Step
We start with the given expression: $7x(x+4)$
We apply the distributive property to multiply the monomial by the binomial: $7x(x)+(4)(7x)$
We multiply the coefficients and add the exponents on each term to arrive at our answer: $$7x^{1+1}+28x$$$$7x^{2}+28x$$
