Question

Heyo! I need some help, please. What is the x coordinate if (x, 17) is on a line that passes through the points (1, 2) and (-1, -8) on a standard (x, y) coordinate plane?

Answer 1

• x = 4

Explanation:

The line with points (1,2) and (-1,-8). Work out its equation.

• y = mx + b

The slope is:

• m = (-8 - 2)/(-1 - 1) = -10/-2 = 5

To find the y intercept, substitute x and y-xoordinates of point (1,2):

• 2 = 5(1) + b
• b = 2 - 5
• b = -3

The line is:

• y = 5x - 3

Point (x, 17), substitute y-coordinate and solve for x

• 17 = 5x - 3
• 5x = 17 + 3
• 5x = 20
• x = 20/5
• x = 4