<p>In the xy-plane, the line with equation y=5x-10 crosses the x-axis at the point with coordinates (a,b). What is the value of a?</p>
<p>D) 12</p>
<p>The collegeboard answer explanation say's to put y=0. My question is do we always put y=0 when a line crosses the x-axis?</p>
<p>The answer you have there is wrong. It should be 2.</p>
<p>Now to answer your question:</p>
<p>Yes! A point on the x-axis has a y-coordinate of 0. If you know how to plot points, then this should be clear to you.</p>
<p>As an exercise, draw a coordinate grid, and plot some points on the x-axis. What do you notice? Now plot some points on the y-axis. What do you notice about these?</p>
<p>So if a point is on the x-axis, then y=0. If a point is on the y-axis, then x=0.</p>
<p>haha you’re right. Sorry about that.</p>
<p>Thank you very much! =)</p>