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Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 decade ago

For anyone who knows how to do functions?

why is it that in this equation d(f) = 4f+130, 130 is the y-intercept and 4 is the slope, yet in another equation in the "y=mx+b" form like y=3x+10, y is the y intercept, and 3 is the slope? That just confuses me even more

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  • 1 decade ago
    Favorite Answer

    let me tell you something sdo u will never be confused ;

    One of the most important properties of straight lines is their angle from horizontal. This concept is called "slope".

    Let's take a look at the straight line y = ( 2/3 )x – 4

    Pick two x's and solve for each corresponding y: If, say, x = 3, then y = ( 2/3 )(3) – 4 = 2 – 4 = –2. If, say, x = 9, then y = ( 2/3 )(9) – 4 = 6 – 4 = 2. (By the way, I picked the x-values to be multiples of three because of the fraction. It's not a rule that you have to do that, but it's a helpful technique.) So the two points (3, –2) and (9, 2) are on the line y = ( 2/3 )x – 4.

    The formula for the slope of the straight line going through the points (x1, y1) and (x 2, y 2) is given by:

    M = ( Y2 - Y1) / (X2 - X1)

    The subscripts refer to the two points.

    (m=rise/run)

    Note:

    Parallel lines have equal slope.

    Perpendicular lines have negative reciprocal slopes.If you visualize a line with positive slope (so it's an increasing line), then the perpendicular line must have negative slope (because it will be a decreasing line). So perpendicular slopes have opposite signs. The other "opposite" thing with perpendicular slopes is that they are reciprocals; that is, you take the one slope, and flip it upside down. Put this together with the sign change, and you get that the perpendicular slope is the "negative reciprocal" of the original slope (and lines with slopes that are negative reciprocals are perpendicular). In numbers, if the one slope is m = 4/5, then the perpendicular slope will be m = –5/4. If the one slope is m = –2, then the perpendicular slope will be m = 1/2.

    NOW YOUR QUESTION ;

    a) if d(f) = 4f+130 ,{ d(f) is y } and y =130 so we have ;

    130 = 4f+130 ; 4f = 130 - 130 ; f4 =0 . f=0/4 ; f=0

    b) 3 is slope as i said b4 , and y is intercept.

    good luck. i hope it could help you.

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  • 1 decade ago

    d(f) = 4f + 130 is a linear function. It may be written in the form

    y(x) = ax + b or more simply y=mx+b.

    If you write f(q) =50q + 20, then 50 is the slope and 20 is the y-intercept

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  • raj
    Lv 7
    1 decade ago

    you are confused

    in y=3x+10,3 is the slope and 10 is the 'y' intercept

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  • 1 decade ago

    don't feel bad, I suck at slope-intersept form. Just rember, you're not alone.

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