document.write( "Question 172963: Here's my problem I need some help!!! When you use y-y=m(x-x). I can do everything except for the final answer. Example: m=7/8,(2,-7)\r
\n" ); document.write( "\n" ); document.write( "I can set up the problem\r
\n" ); document.write( "\n" ); document.write( "y-(-7)=7/8(x-2)
\n" ); document.write( "y-(-7)=7/8x-7/4
\n" ); document.write( "This final step is where I have trouble and can't seem to understand.
\n" ); document.write( "They say to add -7 to 7/4, but how would you get an answer of 35/4? \n" ); document.write( "
Algebra.Com's Answer #127802 by gonzo(654)\"\" \"About 
You can put this solution on YOUR website!
y = m*x = b
\n" ); document.write( "b is the y intercept (value of y when x = 0).
\n" ); document.write( "you have a point and a slope.
\n" ); document.write( "point is (x,y) = (2,-7)
\n" ); document.write( "slope is m = 7/8
\n" ); document.write( "-----
\n" ); document.write( "those are given.
\n" ); document.write( "you have m and you want to solve for b.
\n" ); document.write( "you take the point and you replace y with -7 and you replace x with 2.
\n" ); document.write( "your formula with 7/8 as m becomes:
\n" ); document.write( "y = (7/8)*x + b
\n" ); document.write( "your formula after you replace y with -7 and x with 2 becomes:
\n" ); document.write( "-7 = (7/8)*2 + b
\n" ); document.write( "you solve for b.
\n" ); document.write( "you multiply both sides of the equation by 8 to remove the denominator.
\n" ); document.write( "you get:
\n" ); document.write( "-7*8 = 8*((7/8)*2 + b)
\n" ); document.write( "which becomes
\n" ); document.write( "-56 = 8*(7/8)*2 + 8*b
\n" ); document.write( "which becomes:
\n" ); document.write( "-56 = 7*2 + 8*b
\n" ); document.write( "which becomes:
\n" ); document.write( "-56 = 14 + 8*b
\n" ); document.write( "you subtract 14 from both sides of the equation to get:
\n" ); document.write( "-56 -14 = 14 - 14 + 8*b
\n" ); document.write( "which becomes:
\n" ); document.write( "-70 = 8*b
\n" ); document.write( "you divide both sides of the equation by 8 to get:
\n" ); document.write( "-70/8 = 8*b/8
\n" ); document.write( "which becomes:
\n" ); document.write( "-70/8 = b
\n" ); document.write( "which becomes:
\n" ); document.write( "b = -35/4
\n" ); document.write( "your final equation becomes:
\n" ); document.write( "y = 7/8*x - 35/4
\n" ); document.write( "-----
\n" ); document.write( "if you graph the equation, you should be able to see that.
\n" ); document.write( "graph is shown below:
\n" ); document.write( "when x = 0, y should be -35/4
\n" ); document.write( "as you can see from the graph, it is (-8.75).
\n" ); document.write( "also when y = 0, x should be 10 which you can also see from the graph.
\n" ); document.write( "look below the graph for further comments:
\n" ); document.write( "\"graph+%28800%2C800%2C-5%2C20%2C-15%2C15%2C7%2F8%2Ax-%2835%2F4%29%29\"
\n" ); document.write( "-----
\n" ); document.write( "tracing back what you did:
\n" ); document.write( "m=7/8,(2,-7)
\n" ); document.write( "you set up the problem as:
\n" ); document.write( "y-(-7)=7/8(x-2)
\n" ); document.write( "y-(-7)=7/8x-7/4
\n" ); document.write( "-----
\n" ); document.write( "you used the form: (y-y1) = m*(x-x1) which is good.
\n" ); document.write( "m is 7/8 which is good.
\n" ); document.write( "y1 is -7 which is good.
\n" ); document.write( "x1 is 2 which is good.
\n" ); document.write( "formula becomes:
\n" ); document.write( "y-(-7) = (7/8)*(x-2) which you got ok.
\n" ); document.write( "you seem to also have gotten the next step ok:
\n" ); document.write( "y-(-7) = (7/8)*x - ((7/8)*2)
\n" ); document.write( "which became:
\n" ); document.write( "y-(-7) = (7/8)*x - (7/4)
\n" ); document.write( "so you did ok up until the time you stopped.
\n" ); document.write( "the next step was to remove the parentheses.
\n" ); document.write( "y+7 = (7/8)*x - (7/4)
\n" ); document.write( "the next step was to subtract 7 from both sides of the equation to move it from the left side to the right side.
\n" ); document.write( "y + 7 - 7 = (7/8)*x - (7/4) - 7
\n" ); document.write( "simplifying, 7 on the left cancels out.
\n" ); document.write( "y = (7/8)*x - (7/4) - 7.
\n" ); document.write( "you can multiply both sides of the equation to remove the denominators to get:
\n" ); document.write( "8*y = 8*(7/8)*x - 8*(7/4) - 8*7
\n" ); document.write( "which becomes:
\n" ); document.write( "8*y = 7*x - 2*7 - 8*7
\n" ); document.write( "which becomes:
\n" ); document.write( "8*y = 7*x - 14 - 56
\n" ); document.write( "which becomes:
\n" ); document.write( "8*y = 7*x - 70
\n" ); document.write( "you can then divide both sides of the equation by 8 to get only 1*y on the left side only.
\n" ); document.write( "you get:
\n" ); document.write( "8*y/8 = 7*x/8 - 70/8
\n" ); document.write( "which becomes:
\n" ); document.write( "y = (7/8)*x - (70/8)
\n" ); document.write( "which becomes:
\n" ); document.write( "y = (7/8)*x - (35/4)
\n" ); document.write( "after you simplify (70/8) by dividing numerator and denominator by 2.
\n" ); document.write( "----- \n" ); document.write( "
\n" );