# graphing square roots?

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

Relevance

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....

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