You need to solve system of equations
From second equation we have
So we put that into first equation instead of `y`.
We can wow solve this quadratic equation by using this formula` `
`x_(1,2)=(-b pm sqrt(b^2-4ac))/(2a)`
where `a, b` and `c` are coefficients of equation `ax^2+bx+c=0`.
So in your case
`x_(1,2)=(18pm sqrt(324-180) )/2=(18pm12)/2`
Now by putting this into (1) we get
So your solutions are `(x_1,y_1)=(3,30)` and `(x_2,y_2)=(15,6)`.
Rearrange the second formula to get y on its own
Substitute 'y=36-2x' into the first equation
Move the -2x² and +36x to the other side to turn the -2x² into positive 2x²
Divide the whole equation by 2 to change 2x² to just x² as its easier to deal with.
Factorise this quadratic into brackets.
Two numbers that times together to make 45 and add to make -18 are -3 and -15
x= 3 x= 15
Substitute 3 for x to get 3y=90
Rearrange it to get y= 90/3
The first solution is (3,30)
Now for the second solution substitute 15 into the the equation.
The second solution is (15,6)
The two solutions are (3,30) and (15,6)