1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple high-school math problems

  1. Feb 8, 2007 #1
    Simple high-school math problems!!

    I really need some help!! I am pretty bad at math and am having an awful lot of trouble with my homework.

    1.) How do I graph by stating the x and y intercepts? How do I figure out what those are?

    ex. x + y = 7
    3x - 2y = 6

    2.) How do I graph using the slope intercept form (y = mx + b)?

    ex. y= -2x + 3
    y = x - 2

    3.) And lastly, how do I solve this question

    0.2(4n + 1) = 0.5(n-2)??
    !!!!!!!!! I just realized I posted this in the wrong forum. Sorry
  2. jcsd
  3. Feb 8, 2007 #2
    1) Start with the definition of the x and y intercepts. What do they mean and how do they help you graph?

    2) Look up the form y=mx+b to find out what m and b are, and learn how to find and use them.

    3) Have you used the distributive property before?

    The distributive property says that:

    [tex]a(b + c) = a*b + a*c[/tex]
  4. Feb 8, 2007 #3
    1) x-intercept when y=0
    y-intercept when x=0

    2) They are already in the y=mx + b form
    Say y=2x-3, then m=2 and b=-3
    that is, the gradient is 2 and the y intercept is at y=3 (since x=0, mx=0)
  5. Feb 9, 2007 #4

    Gib Z

    User Avatar
    Homework Helper

    ok dude, it seems like your only doing y=mx+b graphs right now.

    Since theres lines are always straight, we just get any 2 points and draw the line that connects them. any 2 are fine, but x and y ints are easiest to work out, because zeros easy to work with.
  6. Feb 10, 2007 #5
    To find the x-intercept, let y = 0 and solve the equation for x.
    To find the y-intercept, let x = 0 and solve the equation for y.

    In x + y = 7, both the x and y intercepts are 7.

    In 3x - 2y = 6, the x-intercept is 2, and the y-intercept is -3.

    In the equation y = mx + b, m is the slope and b is the y-intercept.

    With regard to y = -2x + 3, you already know that (0,3) is a solution, since 3 is the y-intercept. Simply substitute another value for either x or y, solve the equation, plot the point, and graph the line. This is no different than graphing any other linear equation.

    The same is true for y = x - 2. FYI, the coefficient of x is the slope, so in this case the slope is equal to 1.

    And lastly, how do I solve this question

    You solve it like any other equation. Start by removing the parenthesis by using the distributive property. This property states a(b + c) = ab + ac. So, your equation then becomes:

    0.8n + 0.2 = 0.5n - 1

    From here you can use the subtraction principle to cancel the 0.5n:

    0.3n + 0.2 = -1

    Use that principle again to cancel the 0.2:

    0.3n = -1.2

    Now use the division principle to solve for n:

    n = 4
  7. Feb 10, 2007 #6
    For the future, you should never post full solutions to homework problems.
  8. Feb 10, 2007 #7
    My bad, I'm new to this forum. Sorry about that.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook