Answer:
a) y does NOT vary directly with x
b) y = 2.5x -6.5
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.
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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