Question

How do solve the following linear system?: `-9x+5y=1 , -4x-15y=-1`?

Answer 1

`color(brown)(x = -2/31, y = 13/155`

Explanation:

`-9x + 5y = 1, " Eqn (1)"`

`-4x - 15y = -1 " Eqn (2)"`

Add (3 * Eqn (1) and Eqn (2)),

`3 * -9x +cancel( 3 * 5y) + -4x + cancel(-15y )= 3 *1 + -1`

`--31x = 2 " or " x = -2/31`

Substituting value of x in Eqn (2),

`(-4 * -2/31) - 15y = -1`

`-15y = -39/31`

`y = 39/ 465 = 13/155`