LIM TENG SHUEN ERNEST's answer to Amanda's Secondary 2 Maths Singapore question.
How did you get y=-×+c ? then -1=-3+c
As stated, the general equation for a straight line is y = m x + c where m and c are values to be determined.
Apply the gradient formula using x and y values from the two points given to get gradient = -1
m is the gradient, so substitute m = -1 in the general equation to get y = (-1)x + c
All points on a line must satisfy the line equation. Since (3, -1) is a point on the line, we can substitute x = 3, y = -1 into the equation to get
-1 = (-1)(3) + c
We then simplify and solve to get c = 2 and the final line equation y = -x + 2
Apply the gradient formula using x and y values from the two points given to get gradient = -1
m is the gradient, so substitute m = -1 in the general equation to get y = (-1)x + c
All points on a line must satisfy the line equation. Since (3, -1) is a point on the line, we can substitute x = 3, y = -1 into the equation to get
-1 = (-1)(3) + c
We then simplify and solve to get c = 2 and the final line equation y = -x + 2
I see, thank you!