Question

For the given graph, write down the $x-y$ equations

• A. $y=x$
• B. $y=-x$
• C. $y=2x$
• D. $y=-2x$

Answer 1

The correct option is A $y=x$

The graph corresponds to a straight line

Hence

$\frac{dy}{dx}=m$

Or

$y=mx+C$

Since it passes through the origin

$y=mx$ is the equation of the line.

Also

If $\theta$ is the angle made by the line with positive x axis, then we can see that $tan\theta =tan{45}^0=1$.

Now $tan\theta =m$

Hence $m=1$.

Thus the equation of the given straight line is $y=x$ .