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Write a linear equation! Shortcut! forgot, need to remember?
Minutes: 20, 30, 50, 80, 90
Miles Traveled: 16, 24, 40, 64, 72
Need to make an linear equation if x= minutes and y= miles traveled, I remember there was a shortcut, the top adds by 10 and bottom adds, then use that to make an equation, can someone help me, or help me remember?
Thanks
2 Answers
- MorningfoxLv 71 decade agoFavorite Answer
No, the top line is not in increments of 10. The increments are 10, 20, 30, 10.
The bottom line increments are 8, 16, 24, and 8
Notice that that bottom increments divided by the top increments always gives the same result.
8/10 = 16/20 = 24 / 30 = 8 / 10 That is the slope, 8/10 = 0.8
So the equation is Miles = 0.8 minutes + B
To figure out the last part, plug in one of the pairs of numbers. Like 20 minutes, and 16 miles
16 = 0.8 (20) + B
16 = 16 + B = 16 + 0
So B = 0
- 1 decade ago
Choose two points (an x value and corresponding y value):
(20, 16) & (30, 24)
use slope formula to determine slope of line:
slope(m) = (16 - 24)/(20 - 30) = 4/5
y = mx + b
substitute slope:
y = (4/5)x + b
substitute any value for x and the corresponding y value.
16 = (4/5)20 + b
16 = 16 + b
0 = b
substitute b back in:
y = (4/5)x
choose another x and y pair to check your work:
24 = (4/5)30
24 = 24
and another:
40 = (4/5)50
40 = 40
Each x value is 4/5 of the corresponding y value.
Source(s): Basic algebra knowledge
