Question

If x= 3 and y=-1 is the sollution of the simultaneous equations 3px+ qy = 11, -qx+ 5y =p, find the value of p and of q *

Answer 1

Answer:

Put the values of x and y into the equations and then solve as normal.

9p - q = 11

-3q - 5 = p

As you know p, put this into the first equation

9(-3q -5) - q = 11

-28q - 45 = 11

-28q = 56

q = -2

6 - 5 = p

p = 1

so q = -2, p = 1

hope it helps :)

Answer 2

Answer:

3px+ qy = 11

9p-q=11

27p-3q=33------->1

-qx+ 5y =p

-3q-5=p

-3q-p=5-------->2

by substituting 1 and 2,

27p-3q--3q-p=11-5

26p=6

p=6/26=3/13

substituting p in 9p-q=11,

9×3/13-q=11

27/13 -q=143/13

q=-116/13

p=3/13

q=-116/13