Question 195794
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Write an equation in slope-intercept form of a line containing the point (4,7) and (8,9).


We get the Slope via Point Slope form:
{{{m=(y[2]-y[1])/(x[2]-x[1])=(9-7)/(8-4)=2/4}}}
{{{red(m=1/2)}}}


Thru point (4,7) in Slope-Intercept Form:
{{{y=mx+b}}}
{{{7=(1/cross(2)1)(cross(4)2)+b}}}
{{{7=2+b}}}
{{{b=7-2=red(5)}}}, Y-Inetercept


The same as thru point (8,9):
{{{9=(1/cross(2)1)(cross(8)4)+b}}}
{{{b=9-4=red(5)}}}



It follows, ---> <font color=blue>y = (1/2)x + 5</font>, Answer
{{{drawing(400,400,-10,10,-10,10,grid(1),graph(400,400,-10,10,-10,10,(1/2)x+5),blue(circle(8,9,.15)),blue(circle(4,7,.15)),green(circle(0,5,.12)),green(locate(.5,5,Yintercept)))}}}


Thank you,
Jojo</font>