Question

solve these questions by substitution method :(​

Answer 1

Refer the Attachment For Solution of both Questions.

There is little bit error in second sum.

Correction :

3x - 4y = 11

7x - 5y = +4

Answers :

First Sum : Value of X = 2 & Value of Y = - 3 .

Second Sum : Value of X = - 3 & Value of Y = - 5 .

Step By Step Solution is provided in Attachment .

Answer 2

Hey here is your answer

Question - 1 :-

11x + 15y + 23 = 0

7x - 2y - 20 = 0

Solution :-

11x + 15y + 23 = 0

15y = 0 - 11x - 23

15y = - 11x - 23

y = (- 11x - 23) / 15 -(1)

putting (1) in equation 2

7x - 2y - 20 = 0

7x - 2 (- 11x - 23) / 15 - 20 = 0

7x + (22x + 46) / 15 - 20 = 0

7x + 22x/15 + 46/15 - 20 = 0

(7x × 15 + 22x) / 15 + (46 - 15 × 20) / 20 = 0

(105x + 22x) / 15 + (46 - 300) / 20 = 0

127x / 15 - 254 / 20 = 0

127x / 15 = 254 / 20

x = 254 / 20 × 15 / 127

x = 3 / 2

Question - 2 :-

3x - 4y = 11

7x - 5y = 4

Solution :-

3x - 4y = 11

- 4y = 11 - 3x

y = (11 - 3x) / - 4

y = (- 11 + 3x) / 4 -(1)

putting -(1) in equation 2

7x - 5y = 4

7x - 5(- 11 + 3x) / 4 = 4

7x + (55 - 15x) / 4 = 4

7x + 55/4 - 15x/4 = 4

7x - 15x/4 + 55/4 = 4

(7x × 4 - 15x) / 4 + 55/4 = 4

(28x - 15x) / 4 + 55/4 = 4

13x / 4 + 55/4 = 4

13x / 4 = 4 - 55/4

13x / 4 = (4 × 4 - 55) /4

13x / 4 = (16 - 55) / 4

13x = -39

x = -3

hope this helps you