Question

Direct variation worksheet

Answer 1

Answer:

Part 4) k=1/2

Part 5) k=-2/3

Part 6) y=32

Part 7) x=6

Part 8) v=99

Part 9)b=6

Part 10) y=6

Step-by-step explanation:

we know that

A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form $y/x=k$ or $y=kx$

In a proportional relationship the constant of proportionality k is equal to the slope m of the line and the line passes through the origin

Part 4) Find the value of the constant of proportionality k

we have

$y=\frac{1}{2}x$

Remember that the value of k is the same that the value of the slope

$m=\frac{1}{2}$

so

$k=\frac{1}{2}$

Part 5) Find the value of the constant of proportionality k

we have

$y=-\frac{2}{3}x$

Remember that the value of k is the same that the value of the slope

$m=-\frac{2}{3}$

so

$k=-\frac{2}{3}$

Part 6) Suppose that y varies directly with x, and y=16 when x=8. Find y  when x=16

step 1

Find the value of the constant of proportionality k

$k=y/x$

$k=16/8=2$

step 2

Find the equation of the direct variation

$y=kx$

substitute the value of k

$y=2x$

step 3

Find y  when x=16

$y=2(16)=32$

Part 7) Suppose that y varies directly with x, and y=21 when x=3. Find x  when y=42

step 1

Find the value of the constant of proportionality k

$k=y/x$

$k=21/3=7$

step 2

Find the equation of the direct variation

$y=kx$

substitute the value of k

$y=7x$

step 3

Find x  when y=42

$42=7x$

solve for x

$x=42/7$

$x=6$

Part 8) Suppose that v varies directly with g, and v=36 when g=4. Find v  when g=11

step 1

Find the value of the constant of proportionality k

$k=v/g$

$k=36/4=9$

step 2

Find the equation of the direct variation

$v=kg$

substitute the value of k

$v=9g$

step 3

Find v  when g=11

$v=9(11)=99$

Part 9) Suppose that a varies directly with a, and a=7 when b=2. Find b  when a=21

step 1

Find the value of the constant of proportionality k

$k=a/b$

$k=7/2=3.5$

step 2

Find the equation of the direct variation

$a=kb$

substitute the value of k

$a=3.5b$

step 3

Find b  when a=21

$21=3.5b$

solve for b

$b=21/3.5$

$b=6$

Part 10) Suppose that y varies directly with x, and y=9 when x=3/2. Find y  when x=1

step 1

Find the value of the constant of proportionality k

$k=y/x$

$k=9/(3/2)=6$

step 2

Find the equation of the direct variation

$y=kx$

substitute the value of k

$y=6x$

step 3

Find y  when x=1

$y=6(1)=6$