Question

Help please
Solve each of the following pairs of simultaneous equations for x and y

1) ax+y=c
x+by=d

Answer 1

Multiply the second equation by b and then subtract it from the first equation to eliminate x. Solve for y. Then substitute y in the first equation and solve for x.

Answer 2

@ranga can you give me the work out of it as I don't really understand how it work. Thanks :D

Answer 3

ax + y = c ---- (1)
x + by = d ---- (2)
multiply (2) by a:
ax + aby = ad. Subtract (1):
ax + y = c
subtract
aby - y = ad - c
y(ab - 1) = ad - c
y = (ad - c) / (ab - 1)
Put y in (1)
ax + (ad - c) / (ab - 1) = c
ax = c - (ad - c) / (ab - 1)
= (abc - c - ad + c) / (ab - 1)
= (abc - ad) / (ab - 1)
ax = a(bc - d) / (ab - 1)
divide both sides by a:
x = (bc - d) / (ab - 1)

x = (bc - d) / (ab - 1) and y = (ad - c) / (ab - 1)

Answer 4

@ranga thanks :D

Answer 5

You are welcome.