Question

Solve the following simultaneous equations by eliminating one variable: 1) x + 2y = 21 3x – 2y = 15

Answer 1

$x +2y = 21 - - - - - - (1)$

$3x - 2y = 15 - - - - - - (2)$

$eq(1) + eq(2)$

$\binom{x + 2y = 21}{3x - 2y = 15} => 4x = 36$

$x = \frac{36}{4}$

$|x = 9|$

$sub \: x \: in \: eq(1)$

$9 + 2y = 21$

$2y = 21 - 9 = > 2y = 12$

$y = \frac{12}{2}$

$|y = 12|$

Answer 2

Solve the following simultaneous equations by eliminating one variable: 1) x + 2y = 21 3x – 2y = 15

Y = 12