If 9x + 11y = 51 and 11x + 9y = 49, then x = ………………. A) -

1.	If 9x + 11y = 51 and 11x + 9y = 49, then x = ………………. A) -1 B) -2 C) 1 D) 2
Answer» Correct option is (D) 2 9x + 11y = 51 _________(1) 11x + 9y = 49 _________(2) Multiplying equation (1) by 11 & equation (2) by 9, we get 99x + 121y = 561 _________(3) 99x + 81y = 441 _________(4) Subtract equation (4) from (3), we get 40y = 120 \(\Rightarrow\) y = \(\frac{120}{40}\) = 3 Then from (1), we get 9x + 33 = 51 \(\Rightarrow\) 9x = 51 - 33 = 18 \(\Rightarrow\) x = \(\frac{18}9\) = 2 Correct option is D) 2

If 9x + 11y = 51 and 11x + 9y = 49, then x = ………………. A) -1 B) -2 C) 1 D) 2

Answer»

Correct option is (D) 2

9x + 11y = 51 _________(1)

11x + 9y = 49 _________(2)

Multiplying equation (1) by 11 & equation (2) by 9, we get

99x + 121y = 561 _________(3)

99x + 81y = 441 _________(4)

Subtract equation (4) from (3), we get

40y = 120

\(\Rightarrow\) y = \(\frac{120}{40}\) = 3

Then from (1), we get

9x + 33 = 51

\(\Rightarrow\) 9x = 51 - 33 = 18

\(\Rightarrow\) x = \(\frac{18}9\) = 2

Correct option is D) 2