Question

What is the equation of direct variation given that y is 16 when x is -2

Answer 1

y = -8x is the equation of direct variation given that y is 16 when x is -2

Solution:

If y varies directly as x, then equation of direct variation is given as:

$y \propto x\\\\y = kx ---- eqn\ 1$

Where, k is constant of proportionality

From given,

y = 16 when x = -2

Substitute in eqn 1

$16 = k \times - 2\\\\k = -8$

Thus the equation of direct variation is:

Substitute k = -8 in eqn 1

y = -8x

Thus the equation is y = -8x