Solution:
If y varies directly as x, then equation of direct variation is given as:
[tex]y \propto x\\\\y = kx ---- eqn\ 1[/tex]
Where, k is constant of proportionality
From given,
y = 16 when x = -2
Substitute in eqn 1
[tex]16 = k \times - 2\\\\k = -8[/tex]
Thus the equation of direct variation is:
Substitute k = -8 in eqn 1
y = -8x
Thus the equation is y = -8x
