Question

Find an equation of a line that comes close to the points listed in below. Then use a graphing calculator to check that your line comes close to the points.

x (2,4,5,6,8)

y (12,10,6,6,1)


A.

y = 2 x + 2

B.

y = negative 2 x + 17

C.

y = negative 2 x + 18

D.

y = negative 1.3 x + 15

Answer 1

Option B: y = -2x + 17.

Explanation:

Lets calculate values for option B:

x = 2 , y = -4+17 = 13 ( B gives the value 12)

x = 4, y = -8+17 = 9 (10)

x = 5, y = -10+17 = 7 (6)

x = 6, y = -12+17 = 5 (6)

x = 8, y = -16+17 =- 1 (1)

Sum of the differences = 1 + 1 + 1 + 1 = 4.

These values are close to the ones given in the question.

Option A y = 6, 10, 12, 14, 18 - some of the values of y are a lot different than the given values.

Option C:

Working them out we get y = 14, 10, 8, 6, 2. which are not quite as good as Option B values The total difference is 5 compared with 4 for option B.

Option D.

y = 12.4, 9.8, 8.5, 7.2, 4.6 where some of the differences are large.