Question

Use the elimination method to solve the system of equations. Choose the correct pair

Answer 1

Answer:

D)  (2, -1)

Step-by-step explanation:

12x - y = 25

 9x + y = 17  

21x = 42

x = 2

Plug 2 in for x to find y

18 + y = 17

y = -1

(2, -1)

Answer 2

Explaination :

Here we have been given with two equations and we have to use elimination method to solve them and get the value of x and y respectively.

• 12x - y = 25 (Equation No 1)
• 9x + y = 17 (Equation No 2)

• In Equation No 2 :

Transposing the 9x which is in L.H.S. to R.H.S. it would be negative.

⇒ y = 17 - 9x

• In Equation No 1 :

We will substitute the temporary value of y which we got above here.

⇒ 12x - y = 25

⇒12x - (17 - 9x) = 25

⇒ 12x - 17 + 9x = 25

⇒ 12x + 9x - 17 = 25

⇒ 21x - 17 = 25

⇒ 21x = 25 + 17

⇒ 21x = 42

⇒ x = 42 / 21

⇒ x = 14 / 7

⇒ x = 2

Therefore,

• Value of x is 2.

★ Finding out value of y :

⇒ y = 17 - 9x

⇒ y = 17 - 9(2)

⇒ y = 17 - 9 × 2

⇒ y = 17 - 18

⇒ y = -1

Therefore,

• Value of y is -1

★ Henceforth,

• Option D (2 , -1) is correct.

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