Question

Use the substitution method to solve these simultaneous equations.

a) 3x + 2y = 33
y = 41 - 5x

b) y = 3x - 3
-5x + 3y = 3

c) 4x + y = 9
y = 11 - 5x

d) x = -5 - 2y
5y + x = -11

e) y = 2x + 1
-5x - 4y = 35

Answer 1

Explanation:

a) 3x+2(41-5x)=33 as y=41-5x is given

3x+82-10x=33

-7x+82=33

-7x=33-82

-7x=-49 cut the negative signs as its LHS and RHS

x=49/7=7

b)-5x+3(3x-3)=3 as y=3x-3 is given

-5x+9x-9=3

4x-9=3

4x=3+9

x=12/4=3

c)4x+11-5x=9

-x+11=9

-x=9-11

-x=-2 cut the negative signs as its LHS and RHS

x=2

d) 5y+ -5-2y=-11 as x=-5-2y is given

3y+-5=-11

3y=-11+5

3y=-6

y=-6/3=-2

e)-5x-4(2x+1)=35 as y=2x+1

-5x-8x+4=35

3x+4=35

3x=35-4

3x=31

x=31/3

x=10.3