Find a missing coordinate using slope
key notes:
Slope =change in y / change in x
Learn with an example
A line that includes the points (1,t) and (3,10) has a slope of 9. What is the value of t?
Take the slope formula and plug in the slope and both pairs of (x, y) coordinates. Then solve for t.
Slope =change in y / change in x
9 = 10-t /3-1
9 =10-t/ 2
2×9 = 10-t
18 = 10-t
8 = -t [ Subtract 10 from both sides]
-8 = t [ Divide both sides by –1]
The value of t is –8.
The points (–6,q) and (–5,–7) fall on a line with a slope of –5. What is the value of q?
Take the slope formula and plug in the slope and both pairs of (x, y) coordinates. Then solve for q.
Slope =change in y / change in x
-5 = -7-q /-5 -(-6)
-5 =-7-q [ Simplify]
2 = -q [Add 7 to both sides]
-2 = q [Divide both sides by –1]
The value of q is –2.
A line with a slope of –9 passes through the points (9, – 7) and (8,v). What is the value of v?
v=
Take the slope formula and plug in the slope and both pairs of (x, y) coordinates. Then solve for v.
slope = change in y / change in x
-9 = v – -7 / 8 – 9 Plug in –9, (9, – 7), and (8,v)
-9 = v + 7 / -1 Simplify
-9 = -v – 7 Simplify
-2 = -v Add 7 to both sides
2 = v Divide both sides by -1
The value of v is 2.
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