Post a New Question

Math: Linear Equations

posted by .

What is "3x=9" in y=mx+b form, and what is its slope, y-intercept, and x-intercept? [i think that its x-intercept is (3,0), but i'm not sure about any of the others]

Also, what is the x-intercept of "2y+16=0"? [is it "none"?]

  • Math: Linear Equations -

    I think these are trick questions and you have the right idea.

    3x = 9 is the equation of a vertical line. There is no y in the equation, so there is no "y = mx + b" form for a vertical line. The simplest way to express this line is x = 3.

    Its x-intercept is 3 (because (3, 0) is where the line crosses the x-axis).

    It does not have a y-intercept, because the line never crosses the y-axis.

    Technically, it has an undefined slope.

    Similarly, the other equation is a horizontal line. 2y + 16 = 0 is the same as 2y = -16, or y = -8. This is a horizontal line through (0, -8). It has no x-intercept. The y-intercept is -8. The slope is zero. I think you are right to say that the x-intercept is "none."

  • Math: Linear Equations -

    Thanks!!! No wonder why these questions didn't make much sense and didn't seem quite possible to solve...

  • Math: Linear Equations -

    However, if the equation was this instead ...

    2y + 16x = 0

    ... then you do have a diagonal line that has both an x-intercept and a y-intercept and a slope that is not zero but not undefined. I think it is a negative slope.

    Can you figure out the x-intercept of the line? the y-intercept of the line? and the slope of the line? Hint: When y = 0, what is x? That gives you one intercept. When x = 0, what is y? That gives you another intercept. Draw the line and see if you can find the slope.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

More Related Questions

Post a New Question