tentukan persamaan garis lurus jika diketahui a.memiliki kemiringan 4 dan melalui titik (-2,1) b.melalui (1,4) dan (2,-1) c.melalui (-1,0) dan (3,-8)

a. y - y1 = m(x - x1)
y - 1 = 4(x - (-2))
y - 1 = 4(x + 2)
y - 1 = 4x + 8
y - 4x = 8 + 1
y - 4x = 9
b. y - y1/y2 - y1 = x - x1/x2 - x1
y - 4/-1 - 4 = x - 1/2 - 1
y - 4/-5 = x - 1/1
y - 4/-5 = x - 1
y - 4 = -5(x - 1)
y - 4 = -5x + 5
y + 5x = 5 + 4
y + 5x = 9
c. y - y1/y2 - y1 = x - x1/x2 - x1
y - 0/-8 - 0 = x - (-1)/3 - (-1)
y/-8 = x + 1/3 + 1
y/-8 = x + 1/4
(dikalikan silang)
4(y) = -8(x + 1)
4y = -8x - 8
4y + 8x = -8