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

One solution

Explanation:

I took the quiz

Answer 2

Option- one is correct.

The given system of equations have one solution that is (7,-21)

Explanation:

Given system of equations are

`y=-3x\hfill (1)`

`-9x-4y=21\hfill (2)`

Now to the solution:

To solve the given system of equations using substitution method.

That is substitute equation(1) in equation (2) we get

`-9x-4(-3x)=21` (here y=-3x)

`-9x+12x=21`

`3x=21` (adding the like terms)

`x=(21)/(3)`

Therefore x=7

Now substitute x=7 in equation (1) we get

`y=-3x`

`y=-3(7)`

`y=-21`

Therefore the solution is (7,-21)

Therefore Option- one is correct.

The given system of equations have one solution that is (7,-21)