Algebra
posted by Emma on .
Can you please help me understand this? Thanks
Find the value of y so that the passing line through the two points has the given slope.
1. (2,y) (3,3) ;m=2

Twopoint form of linear equation :
y  y1 = ( y2  y1 ) * ( x  x1 ) / ( x2  x1 )
Add y1 to both sides
y  y1 + y1 = ( y2  y1 ) * ( x  x1 ) / ( x2  x1 ) + y1
y = ( y2  y1 ) * ( x  x1 ) / ( x2  x1 ) + y1
Alopeintercept form of linear equation :
y = m x + b
In this case :
x1 = 2
y1 = y
x2 = 3
y2 = 3
m = ( y2  y1 ) / ( x2  x1 ) = 2
( 3  y ) / ( 3  2 ) = 2
( 3  y ) / 1 = 2
3  y = 2 Subtract 2 to both sides
3  y  2 = 2  2
1  y = 0 Add y to both sides
1  y + y = 0 + y
1 = y
y = 1 
just find the slope for the two points, set it equal to 2
(y3)/(23) = 2  (y3)/1 = 2
y3 = 2
y = 1