Question

Draw the graph of $y=2x^2$ and find the value of $\sqrt{5}$ using the graph.

Answer 1

Step 1: Prepare the table of values for $y=2x^2$

$x$ $0$ $1$ $-1$ $2$ $-2$ $\sqrt{5}$

$y$ $0$ $2$ $2$ $8$ $8$ $10$

Step 2: Plot all the points on the graph sheet and draw the parabola
Step 3: When $x=\sqrt{5},y=2(\sqrt{5}{)}^2=10$
Draw the straight line $y=10$ parallel to x-axis.
Step 4: From the intersecting points of the parabola and the straight line, draw perpendiculars to the x-axis.
The point on x-axis at which the perpendiculars meets are the value of $\sqrt{5}$.
$x=\pm 2.3$
$\therefore \sqrt{5}=\pm 2.3$