1.56: Estimate roots using a graph

(a) Complete the table of values for $y=2^x-4$, giving your answers to 2 decimal places.

(b) On the grid opposite, draw the graph of $y=2^x-4$ for $0\le x\le3$. (2)

(c) Use your graph to obtain an estimate, to one decimal place, of the value of $\log_2 7$. Show clearly how you used the graph. (3)

(d) By drawing a straight line on your graph, obtain an estimate to one decimal place of the root of the equation $2^x+3x=7$ in the interval $0\le x\le3$. (4)