Final answer:
To find the x-intercept of an equation such as y = mx + b, you set y to 0 and solve for x. For an equation y = 7x + 21, the x-intercept would be (-3, 0) when y is zero.
Step-by-step explanation:
We seem to have a little confusion in the question as it includes several unrelated pieces, but the core request is to find the x-intercept. To find the x-intercept of a line, set the y-value to 0 and solve for x.
Assuming the equation we are working with is of the form y = mx + b, where m is the slope and b is the y-intercept, the x-intercept would be the value of x when y is zero.
In a scenario where our equation was y = 7x + 21, setting y to 0 would give us 0 = 7x + 21.
Solving for x, we subtract 21 from both sides to get -21 = 7x, then divide both sides by 7, yielding x = -3. So the x-intercept here would be (-3, 0).
To clarify, the y-intercept occurs where the line crosses the y-axis, and this is typically when x equals zero. However, the x-intercept is the value of x when y equals zero, which is the point we calculate as described above.