Question: how to know the x and y intercepts?
Answer: To determine the x-intercept, we set y equal to zero and solve for x. Similarly, to determine the y-intercept, we set x equal to zero and solve for y. ... 
To find the x-intercept, set y = 0 \displaystyle y=0 y=0.
To find the y-intercept, set x = 0 \displaystyle x=0 x=0.