If 2x² – 2y = 125 and x - y = 2.5, find the value of
x + y

We can solve this using substitution.

because x-y=2.5

x=y+2.5

Now substitute x into other equation.

2(y+2.5)^2-2y=125

2y^2+10y+12.5-2y=125

2y^2+8y-112.5=0

Now comes the ugly part

y=-4+-sqrt(16+900)

y=-4+-sqrt916

y=-4+-2sqrt229

x=-1.5+-2sqrt229

up

step-by-step explanation:

the orientation of the parabolas can easily be found by analysing the power of x and y and their signs. if x is squared , parabola opens up and also if its coefficient is negative it opens down. if y is squared , the parabola opens right and also if its coefficient is negative it opens left. however in order to do the above analysis our equation must be in standard form .

our parabola is

which is not standard form of any parabola . hence we square on both hand side and convert it into standard form.

hence we see that x is squared and its coefficient is non negative . there for it opens up.