Question

(1) If y varies directly as x, and x = 3 and y = 9, solve for k

Answer 1

Answer:

$(1)y=\dfrac{1}{3}x\\\\(2)y=\dfrac{36}{x}$

Step-by-step explanation:

(1)

$y \propto x\\y=kx\\ When x=3 and y=9\\9=3k; Therefore: k=\frac{1}{3} \\ The equation that relates x and y is: \\y=\dfrac{1}{3}x$

(2)

$y \propto \frac{1}{x}\\y = \frac{k}{x}\\ When x=3 and y=12 \\12 = \frac{k}{3}; Therefore: k=3*12=36 \\ The equation that relates x and y is: \\y=\dfrac{36}{x}$

Question 3 is a repetition of Question 2.