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16 votes
What is the equation of the line passing through the points (Two-fifths, StartFraction 19 Over 20 EndFraction) and (one-third, StartFraction 11 Over 12 EndFraction) in slope-intercept form

User Dave Graves
by
3.1k points

1 Answer

21 votes
21 votes

Answer: y = 1/2x + .75

Step-by-step explanation:

Slope-intercept form: y = mx + b

Step 1: Find the slope.

Solve for
(y2-y1)/(x2-x1)


y2-y1 = (11)/(12) -(19)/(20)


x2-x1 = (1)/(3) -(2)/(5)

To solve for the fractions you need a common denominator.


y2-y1 = (11*20)/(12*20) -(19*12)/(20*12) = (220)/(240) -(228)/(240)=(-8)/(240) = (-1)/(30)


x2-x1 = (1*5)/(3*5) -(2*3)/(5*3) = (5)/(15) -(6)/(15)=(-1)/(15)

To divide fractions you keep (the first equation), change (the division sign to multiplication), and flip (the second fraction).


(y2-y1)/(x2-x1)=((-1)/(30) )/((-1)/(15) ) = (-1)/(30)*(15)/(-1) =(-15)/(-30)=(1)/(2)

Step 2: Plug slope and a point into y=mx+b to solve for b.


(11)/(12) = (
(1)/(2))*(
(1)/(3))+b


(11)/(12) = (
(1)/(6))+b


(11)/(12)-(1)/(6) = b


(11*6)/(12*6)-(1*12)/(6*12)=(66)/(72) -(12)/(72) =(54)/(72)=.75

b = .75

y =
(1)/(2)+.75

User Oleg Golovanov
by
2.4k points