Question

Can someone please check if my equation answer is correct?

Answer 1

I am to determine the equation of a line. The question states: The line passes through the points (-1, 3) and (4, 7).
Here is my answer:
\[Slope: m = \frac{ 3 - 7 }{ -1 - 4 } = \frac{ -4 }{ -5 }\]
Substitute into y = mx+b to get: \[y = -\frac{ 4 }{ 5 }x+b\] To find the "b" value, substitute one of the given points. (I chose (-1, 3).)
Substitute x = -1 and y = 3 into y = -4/5x+b to get: 3 = -4/5(-1)+b. Solve for "b".
\[3 = -\frac{ 4 }{ 5 }(-1)+b\]\[3 = \frac{ 4 }{ 5 }+b\]Find a common denominator on the left side (15).
\[3+\frac{ 4 }{ 5 }=b\]\[\frac{ 45 }{ 15 }+\frac{ 4 }{ 15 }=b\]\[\frac{ 49 }{ 15 }=b\]So, the final equation is: \[y = -\frac{ 4 }{ 5 }x + \frac{ 49 }{ 15 }\]
...I'm not entirely sure I got this answer correct, and I do seem to feel I went wrong somewhere as the last fraction is much larger than the first, but again, I'm a little uncertain about all of it. If I could get anyone to check my answer or tell me where I went wrong, I would appreciate it very much!!

Answer 2

formula
Equation of a line
y - y = m (x -x)

you dont use slope intercept formula

Answer 3

Ah, I see... I suppose I used the formula I did through an example in the book. How would I go about using the formula you mentioned, if you don't mind me asking...?

Answer 4

well you got the slope right
just do the same thing

Answer 5

Hmm, I see! Thank you for your explanation! I'll get to getting back into re-answering the question tonight and work on it for a bit for now. I will give you a medal, thank you for taking your time to answer this, I really appreciate letting me know which formula to use!