Question

what is an equation of the line whose graph is shown?

y = x
y = -x
y = 2
y = 2x

Explanation:

Step1: Identify line points

The line passes through $(1,1)$ and $(-1,-1)$.

Step2: Calculate slope

Slope $m = \frac{y_2-y_1}{x_2-x_1} = \frac{1-(-1)}{1-(-1)} = \frac{2}{2}=1$

Step3: Find y-intercept

The line crosses the origin $(0,0)$, so $b=0$.

Step4: Write line equation

Using $y=mx+b$, substitute $m=1, b=0$: $y = x$

Answer:

A. $y = x$