Target Mathematics

1.43: Estimate roots using a graph

4PM1/1/January/2017 — Question 7 · 11 marks

1.43 diagram 1
(a) Complete the table of values for y=ln⁡(5x+1)+2y=\ln(5x+1)+2 giving your answers to 2 decimal places.
xx01234567
yy24.404.775.045.43
(2)
(b) On the grid opposite draw the graph of y=ln⁡(5x+1)+2y=\ln(5x+1)+2 for 0≤x≤70\le x\le7. (2)
(c) By drawing an appropriate straight line on the grid, obtain an estimate, to 1 decimal place, of the positive root of the equation ln⁡(5x+1)−x=0\ln(5x+1)-x=0 in the interval 0≤x≤70\le x\le7. (3)
(d) By drawing an appropriate straight line on the grid, obtain an estimate, to 1 decimal place, of the root of the equation e(3x−1)=5x+1e^{(3x-1)}=5x+1 in the interval 0≤x≤70\le x\le7. (4)