Question

How many solutions does this system have?

y = negative 3 x. Negative 9 x minus 4 y = 21
one
two
an infinite number
no solution

Answer 1

Sorry but the answer is : two.

Substitute $y=-3x$.

$3y-4y=21$

∴$y=-21$

$-3x=-21$

∴$x=7$

The system equation has two solutions $x=7$ and $y=-21$.