Question 38·Medium·Linear Equations in Two Variables
A line passes through the points and in the -plane. What is the slope of the line?
For slope questions with two points, immediately write the slope formula and plug in the coordinates, carefully tracking signs and the order of the points. Compute the numerator and denominator separately, then simplify the fraction and check that the sign (positive or negative) matches the way the line moves from left to right. Avoid common mistakes like swapping - and -changes or dropping minus signs.
Hints
Use the slope formula
Remember that the slope between two points is "change in over change in ": .
Choose and label your points consistently
Pick one point to be and the other to be —it does not matter which you call which, as long as you stay consistent in the formula.
Compute numerator and denominator carefully
Find and separately, being careful with subtracting negative numbers, then put them into the fraction and reduce it.
Desmos Guide
Compute the slope directly in Desmos
In the expression line, type (-1 - 5)/(7 - (-3)) and press Enter. Desmos will display a decimal value for this fraction.
Match the Desmos value to an answer choice
Convert the decimal Desmos shows into a simplified fraction in your head or on paper, and then select the answer choice whose fraction is equal to that value.
Step-by-step Explanation
Recall the slope formula
For a line passing through two points and , the slope is given by
This is often described as "rise over run" (change in over change in ).
Assign coordinates to and
Let be and be .
So:
- ,
- ,
Compute the change in and the change in
Use the formula parts:
- Change in :
- Change in :
Form the slope fraction and simplify
Now plug these into the slope formula:
Simplify by dividing numerator and denominator by :
So, the slope of the line is .