The straight line given by y equals 2x plus 6 is drawn. At which x value does it cross the x-axis?

1. Only two points are needed to plot a straight line graph, and the easiest two are the intercepts. 2. Every point on the horizontal axis has a y value of zero. 3. So set y equal to zero in the equation. 4. That gives zero equal to two x plus 6. 5. Subtract 6 from both sides to get minus 6 equal to two x. 6. Divide both sides by 2 to get x equal to minus 3. 7. The line therefore crosses the horizontal axis at the point where x is minus 3. 8. Answering positive 3 drops the minus sign, and answering minus 6 forgets to divide by the coefficient of x. _Source: Siyavula Mathematics Grade 10 (Everything Maths, CC BY 4.0), Chapter 6: Functions_