10) f(x) = mx + b is a linear equation passing by the point b (on y-axis)
In the example f(x) = 4x means that b=0 & hence it passes by the origin, It is always increasing since its coefficient (or the slope) is positive & equal 4.
So the answer is F
11) the highest the coefficient (or slope) the greater is the rate of change , so it is answer I with m=4 (which is greater than (-1/2)