16) f(x)=x^2+5x g(x)=4x Find (fcirc g)(x)

To find $(f \circ g)(x)$, we need to substitute $g(x)$ into $f(x)$.<br /><br />Given:<br />$f(x) = x^2 + 5x$<br />$g(x) = 4x$<br /><br />Substitute $g(x)$ into $f(x)$:<br />$(f \circ g)(x) = f(g(x)) = f(4x)$<br /><br />Now, substitute $4x$ into $f(x)$:<br />$(f \circ g)(x) = (4x)^2 + 5(4x)$<br /><br />Simplify the expression:<br />$(f \circ g)(x) = 16x^2 + 20x$<br /><br />Therefore, $(f \circ g)(x) = 16x^2 + 20x$.