Question

A ski resort is building two parallel straight ski slopes for children. One of them has a gradient of 1/3. The other ski slope will pass through points (2,-3) and (s,-5). Find the value of s

Answer 1

Answer: s= -8

Step-by-step explanation:

The gradient of the ski slope can ge used as the slope (literally) of a line equation:

y = mx + b,

where m is the slope and b the y-intercept (the value of y when x = 0).

The first slope would be y = -(1/3)x + b.

The slope is (-1/3) since the ski run is headed downhill.  The second ski slope is assumed to have the same gradient ("two parallel straight ski slopes").

y' = -(1/3)x' + b

We may assume that b is the same for both slopes - they start and end at the same point.

We can find b by using the given point (2,-3):

y' = -(1/3)x' + b

-3 = -(1/3)(2) + b

-3 = -(2/3) + b   [Add -(2/3) to both sides: (-3 + 2/3 = -9/3 + 2/3 = -7/3]

-7/3 = b

b = -(7/3)

The second ski slope, y', thus has the equation

y' = (1/3)x' -(7/3)

We want the value of s in (s, -5).

y' = (1/3)x' -(7/3)

-5 = (1/3)s -(7/3)

(1/3)s = -5 +(7/3)    [-15/3 + 7/3 = -8/3]

(1/3)s = -(8/3)    [Multiply both dies by 3]

s = -(24/3)  

s = -8