Question

Q.11: Using the method of elimination by substitution, solve the following
system
5x- 6y+18 = 0
3x + 8y + 5 = 0​

Answer 1

Answer:

5x - 6y = -18 and 3x + 8y = -5

Now,

3x + 8y = -5

→ 3x = -5 - 8y

→ x = (-5-8y)/3 ------- (i)

Then,

5x - 6y = -18

Substituting the value of x from (i)

→ 5 ( -5-8y)/3 - 6y = -18

→ 5/3 × (-5-8y) - 6y = -18

→ -25/3 - 40y/3 - 6y = -18

→ -40y/3 - 6y = -18 + 25/3

→ (-40 - 18)y/3 = (-54 + 25)/3

→ -58y = -29 [ 3 gets cancelled ]

→ y = 29/58

→ y = 1/2

Now,

x = (-5-8y)/3 [ from (i) ]

→ x = (-5-8×1/2)/3

= (-5 - 4)/3

= -9/3

= -3

Hence, x = -3 and y = 1/2