SOLUTION: I need help with Lines. Question is: Find the slope and y-intercept of each line. y = 2x + 3 I have the answer in the book, However I want to know how they came up with it? Answe

Algebra ->  Linear-equations -> SOLUTION: I need help with Lines. Question is: Find the slope and y-intercept of each line. y = 2x + 3 I have the answer in the book, However I want to know how they came up with it? Answe      Log On


   

Question 4145: I need help with Lines.
Question is: Find the slope and y-intercept of each line. y = 2x + 3 I have the answer in the book, However I want to know how they came up with it? Answer:Slope = 2
y-intercept = 3
Thank you
Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
this looks fine so far: x%5E2+%2B+%28x%2B1%29%5E2+%2B+%28x%2B3%29%5E2+=+38. Now multiply all the brackets out:

x%5E2+%2B+x%5E2+%2B+2x+%2B+1+%2B+x%5E2+%2B+6x+%2B+9+=+38
3x%5E2+%2B+8x+%2B+10+=+38
3x%5E2+%2B+8x+-+28+=+0. Now hopefully this factorises nicely. If not --> have to use the quadratic formula. Luckily, it does factorise into:

(3x + 14)(x - 2) = 0

so, 3x+14 = 0 or x-2 = 0

so 3x = -14
--> x = -14/3...mathematically correct but physically wrong for our question.

and the other solution is x=2.

AND NOW check your answer: 3 fields are 2, 3 and 5 km so their areas are: 4, 9 and 25 km^2 --> total is 38km^2, which is correct.

jon.