Question

Solve the equation $y=-3x^2$ graphically.

Answer 1

Let us assign the integer values from $-3$ to $3$ for $x$ and form the following table:

$x$	$-3$	$-2$	$-1$	$0$	$1$	$2$	$3$
$x^2$	$9$	$4$	$1$	$0$	$1$	$4$	$9$
$y=-3x^2$	$-27$	$-12$	$-3$	$0$	$-3$	$-12$	$-27$

Plot the points $(-3,-27),(-2,-12),(-1,-3),(0,0),(1,-3),(2,-12)$ and $(3,-27)$
Join the points by a smooth curve.
The curve thus obtained, is the graph $y=-3x^2$
Note:
(1) The graph of $y=-3x^2$ does not lie above the x-axis as $y$ is always negative.
(2) The graph is symmetrical about y-axis.