數學 Slope intercept

YipWing yan

2013-06-03 12:33 pm

Plaese show all clear steps.

Multiple Choice

1) Determine the slope-intercept form of the line that passes through the point(-4,3) and is parallel to the segment that joins A(-1,-5) and B(-3,1).
A. y=-3x-9
B. y=-3x+5
C. y=-3x+15
D. y=3x+15

2) A hot-dog stand owner makes a profit of $100 when he sells 90 hot dogs a day. He has a loss of $30 when he sells 25 hot dogs a day. Which linear relation respresents his profit?
A. y=0.5x+55
B. y=1.08x+3.08
C. y=1.11x
D. y=2x-80

Please show all clear steps,thank you :)

Extra question: 呢d數學題係香港係屬於幾年級？

回答 (1)

用戶83992

2013-06-03 1:51 pm

✔ 最佳答案

1)
given point A and point B,
so, slope m = (-5-1)/(-1-(-3))
= -6/2
= -3
then, y-3 = -3(x+4)
y-3 = -3x - 12
y = -3x - 9
answer: A
2)
y = mx + b where y is profit and x is hot-dog sold.
100 = 90m + b [1]
-30 = 25m + b [2]
[1]-[2]
130 = 65m
m = 2
so, D is the only answer that has slope m = 2.
answer: D

I believe people learn these math concepts in around 6th grade.

參考: me

👍 0 👎 0