Question

How do you find the solution of the system of equations `y = 4-x^2` and `3x+y = 0`?

Answer 1

Given
`"[1] "y=4-x^2`
`"[2] "3x+y=0`

Rearranging `"[2]"`
`"[3] "y=-3x`

Substituting `"[3]"` into `"[1]"`
`"[4] "-3x = 4 - x^2`

Rearranging `"[4]"`
`"[5] " x^2-3x-4 = 0`

Factoring the left-hand side of `"[5]"`
`"[6] "(x-4)(x+1) = 0`

Solution:
`x=4` or `x=-1`