Question

Learning

Diagnostic
Analytics
Recommendations
Math
La Language arts
El Common Core
Algebra 1
>
S.5 Find a missing coordinate using slope 5C7
Learn with an example
A line that includes the points (-5, u) and (-4, 3) has a slope of -3. What is the value of u?
Submit

Answer 1

The value of u is 6

Explanation:

The rule of the slope of a line is
`m=(y_(2)-y_(1))/(x_(2)-x_(1))` , where

`(x_(1),y_(1))` and
`(x_(2),y_(2))` are two points on the line

Let us use this rule to solve the question

∵ The slope of the line is -3

∴ m = -3

∵ The two points on the line are (-5, u) and (-4, 3)

∴
`x_(1)` = -5 and
`x_(2)` = -4

∴
`y_(1)` = u and
`y_(2)` = 3

→ Substitute these values in the rule of the slope above

∴
`-3=(3-u)/(-4-(-5))`

∴
`-3=(3-u)/(1)`

→ By using cross multiplication

∴ -3 × 1 = 3 - u

∴ -3 = 3 - u

→ Add u to both sides to move u from the right side to the left side

∴ -3 + u = 3 - u + u

∴ -3 + u = 3

→ Add 3 to both sides to move -3 from the left side to the right side

∴ -3 + 3 + u = 3 + 3

∴ u = 6

The value of u is 6