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37 votes
A (-2,y) B (4,-6), gradient: -1/6
Find y using the cross-multiply method

User Joe Huang
by
2.5k points

1 Answer

11 votes
11 votes

Key Ideas

  • Finding a coordinate point given the gradient/slope
  • Cross multiplication
  • Slope equation

We use the slope equation to solve for the slope/gradient of a line:


m=(y_2-y_1)/(x_2-x_1)

  • m = the slope

  • (x_1,y_1) and
    (x_2,y_2) are two points that fall on the line

Solving the Question

We're given:

  • A (-2,y)
  • B (4,-6)
  • Gradient =
    -(1)/(6)


m=(y_2-y_1)/(x_2-x_1)

Plug in the given information:


-(1)/(6)=(-6-y)/(4-(-2))\\\\-(1)/(6)=(-6-y)/(4+2)\\\\-(1)/(6)=(-6-y)/(6)

Cross multiply (by multiplying the numerators by the opposite denominators):


-(1)/(6)=(-6-y)/(6)\\\\-1* 6=6(-6-y)\\-6=-36-6y\\30=-6y\\y=-5

Answer

y = -5

User Yacola
by
2.6k points