Determine the equation of the straight line...?

Question

(in the form y=mx+c)
a) with gradient 4/5 and y-intercept at (0,9)
b) with gradient 2 and passing through the point (3,2)
c) passing through two points (2,5) and (-1,7)
d) parallel to the line 5x-4y+1=0 and passing through the point (o, -5)

I have already completed the question but I just wanted if you'd be so kind as to help me check them as I'm not entirely sure on the answers of some of them. Thankyou.

Answer 1

a) y = (4/5)x + 9, oops my bad. =).

b) y = 2x - 4

c) y = (19 - 2x)/3

d) y = (5x/4) - 5

basically just use the y - y1 = m(x - x1)

Answer 2

Question a)
y = (4/5) x + 9

Question b)
y - 2 = 2(x - 3)
y = 2x - 4

Question c)
m = (7 - 5 ) / (-1 - 2) = - 2 / 3
y - 5 = -2/3 (x - 2)
y - 5 = (-2/3) x + 4/3
y = (-2/3) x + 19/3

Question d)
Given line has m = 5/4 and passes thro` (0,- 5)
y + 5 = (5/4) x
y = (5/4)x - 5

Answer 3

aaazian answer to: a) is WRONG! only the 4 gets divided through by 5, the 9 remains separate to satisfy the point (0,9)

a) y = (4/5)x + 9

b) y = 2x - 4

c) y = (-2/3)x + (19/3)

d) y = (5/4)x - 5

the best way to check for yourself is to sub in one of the co-ordinates given and check if ur equation gives u the other co-ordinate that is given.
good-luck