graphing square roots?

how do i graph y=-9 square root of x?

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  • 1 decade ago
    Favorite Answer

    y=-9sqrt(x), x=0 =>y=0, x=1=>y=-9 , x=4=>y=-18, x=9=>y=-27, x=16=>y=-36..........graphing the points (0,0), (1,-9), (4,-18) , (9,-27)..and goooo....

  • 1 decade ago

    try plotting x in terms of y instead.

    y = -9 * sqrt(x)

    sqrt(x) = 1/9 * -y

    now, we know we can't plot a square root that's negative.

    So, left hand side (LHS) has to be +ive.

    Hence, RHS has to be +ive

    to do that, we've got only one choice: take -ive values of y.

    Again, the sqrt(x) tells us we can only consider +ive values of x.

    +x, -Y :: the graph lies in quadrant-4 (lower right)

    And now, knowing our limits, we can square both sides.

    y = -9 * sqrt(x)

    y^2 = (-9)^2 * x

    y^2 = 81x

    x = 1/81 * y^2

    this is in the form x = a*y^2, a parabola.

    consider it like this: when y is 1, x is 1..

    when y is 2, x is 4. So, x increases as square of y. The 1/81 simply flattens the curve a bit.

    try searching for online grap-plotters; else download this good plotting (and maths all-in-1) software: GraphCalc

  • Anonymous
    1 decade ago

    its a stretch of 9 in the y direction of the graph square root x which looks like a c, with the vertex going through the origin. U can sketch it from this. for more accuracy substitue values for x i.e. 1,2,3.... into the equation and plot with the corresponding y values.

  • 1 decade ago
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  • ZZ
    Lv 4
    1 decade ago

    It should look like a parabola or hyperbola or something like that.

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