Question

Determine whether y varies directly with x. Find the constant of variation. Write the function rule x 5 7 9 y 6 11 16

Answer 1

Answer:

  a)  y does NOT vary directly with x

  b)  y = 2.5x -6.5

Step-by-step explanation:

If variation were direct the ratios of y to x would be constant. They are not:

  6/5 ≠ 11/7

y does not vary directly with x.

__

y changes by 5 from 6 to 11 when x changes by 2 from 5 to 7. Then the slope of the linear function rule is (change in y)/(change in x) = 5/2. Using a point-slope form of the equation of a line, we can write the rule as ...

  y = m(x -h) +k . . . . . . . . for a line of slope m through point (h, k)

  y = (5/2)(x -5) +6

  y = 2.5x -6.5 . . . . . simplify