Question

Simple equations elimination method and substitution method x+y=,3x-2y=7

Answer 1

Given: equations x + y = 4, 3x - 2y = 7

To find: solution by elimination and substitution method

Solution:

Elimination method.

• x + y = 4 ... ...(1)
• 3x - 2y = 7 ... ...(2)

Multiplying (1) by 3 and (2) by 1, we get

• 3x + 3y = 12
• 3x - 2y = 7

On subtraction, we get

• 5y = 5 or, y = 1

Putting y = 1 in (1), we get

• x + 1 = 4
• or, x = 3

Answer: Required solution is x = 3 and y = 1.

Substitution method.

• x + y = 4 ....(1)
• 3x - 2y = 7 ....(2)

From (1), we get x = 4 - y

Substituting x = 4 - y in (2), we get

• 3 (4 - y) - 2y = 7
• or, 12 - 3y - 2y = 7
• or, 5y = 5
• or, y = 1

Answer: Required solution is x = 3 and y = 1.