Question 190109


First let's find the slope of the line through the points *[Tex \LARGE \left(1,2\right)] and *[Tex \LARGE \left(3,3\right)]



Note: *[Tex \LARGE \left(x_{1}, y_{1}\right)] is the first point *[Tex \LARGE \left(1,2\right)] and *[Tex \LARGE \left(x_{2}, y_{2}\right)] is the second point *[Tex \LARGE \left(3,3\right)].



{{{m=(y[2]-y[1])/(x[2]-x[1])}}} Start with the slope formula.



{{{m=(3-2)/(3-1)}}} Plug in {{{y[2]=3}}}, {{{y[1]=2}}}, {{{x[2]=3}}}, and {{{x[1]=1}}}



{{{m=(1)/(3-1)}}} Subtract {{{2}}} from {{{3}}} to get {{{1}}}



{{{m=(1)/(2)}}} Subtract {{{1}}} from {{{3}}} to get {{{2}}}



So the slope of the line that goes through the points *[Tex \LARGE \left(1,2\right)] and *[Tex \LARGE \left(3,3\right)] is {{{m=1/2}}}



Now let's use the point slope formula:



{{{y-y[1]=m(x-x[1])}}} Start with the point slope formula



{{{y-2=(1/2)(x-1)}}} Plug in {{{m=1/2}}}, {{{x[1]=1}}}, and {{{y[1]=2}}}



{{{y-2=(1/2)x+(1/2)(-1)}}} Distribute



{{{y-2=(1/2)x-1/2}}} Multiply



{{{y=(1/2)x-1/2+2}}} Add 2 to both sides. 



{{{y=(1/2)x+3/2}}} Combine like terms. note: If you need help with fractions, check out this <a href="http://www.algebra.com/algebra/homework/NumericFractions/fractions-solver.solver">solver</a>.



{{{y=(1/2)x+3/2}}} Simplify



So the equation that goes through the points *[Tex \LARGE \left(1,2\right)] and *[Tex \LARGE \left(3,3\right)] is {{{y=(1/2)x+3/2}}}



 Notice how the graph of {{{y=(1/2)x+3/2}}} goes through the points *[Tex \LARGE \left(1,2\right)] and *[Tex \LARGE \left(3,3\right)]. So this visually verifies our answer.

 {{{drawing( 500, 500, -10, 10, -10, 10,
 graph( 500, 500, -10, 10, -10, 10,(1/2)x+3/2),
 circle(1,2,0.08),
 circle(1,2,0.10),
 circle(1,2,0.12),
 circle(3,3,0.08),
 circle(3,3,0.10),
 circle(3,3,0.12)
 )}}} Graph of {{{y=(1/2)x+3/2}}} through the points *[Tex \LARGE \left(1,2\right)] and *[Tex \LARGE \left(3,3\right)]