SOLUTION: If a stock price goes from $10 to $12 from January 1st to January 31st, and from $12 to $9 February 1st to February 28th, is the price change from $10 to $9 a straight line?. How

Algebra ->  Functions -> SOLUTION: If a stock price goes from $10 to $12 from January 1st to January 31st, and from $12 to $9 February 1st to February 28th, is the price change from $10 to $9 a straight line?. How      Log On


   

Question 884575: If a stock price goes from $10 to $12 from January 1st to January 31st, and from $12 to $9 February 1st to February 28th, is the price change from $10 to $9 a straight line?.
How can i use two pieces of lines to describe the price movements from the beginning of January to the end of February.
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
for January we have two points (1, 10) and (31, 12)
For February we have two points (1, 12) and (28, 9)
slope(m) is (y2 - y1) / (x2 - x1)
slope for January is ((12 - 10) / (31 - 1) = 2/30 = 1/15
slope for February is (9 - 12) / (28 -1) = -3/27 = -1/9
equation of line for January is y = x/15 +b
use first January point 10 = 1/15 + b and b = 9.93
January line formula is y =x/15 +9.93 (red line graph)
equation of line for February is y = -x/9 +b
use first February point 12 = -1/9 + b and b = 12.11
February line formula is y = -x/9 + 12.11 (green line graph)
Here is a graph of both lines
+graph%28+300%2C+200%2C+-40%2C+40%2C+-20%2C+20%2C+x%2F15+%2B9.93%2C+-x%2F9+%2B12.11%29+
You can see that there are two strait lines that intersect