y = −x^2 + 4 y = 2x + 1
How would you solve by elimination or substitution?

Question

y = −x^2 + 4 y = 2x + 1
How would you solve by elimination or substitution?

rvc · Answer

we have : $$\rm y=-x^2+4~ and ~y=2x+1$$

anonymous · Answer

yes, I don't get how you would solve them though

rvc · Answer

so we have two values for y

rvc · Answer

we can put any of those

anonymous · Answer

like $$-x^2+4=2x+1$$

rvc · Answer

yes

rvc · Answer

now solve further :)

anonymous · Answer

but how would you subract them. Thats what im stuck on.

rvc · Answer

here it is : 
$$\rm 2x+1+x^2-4$$

anonymous · Answer

that is what y equals then right?

rvc · Answer

no 
since when we solve the equation we are left only with x.
then we will put the value of x in any one of the original equation to find the value of y

anonymous · Answer

Im really stuck then .. how would you find what x and y are?

rvc · Answer

here it is :
$$\sf x^2+2x-3=0$$

rvc · Answer

we have to solve the quadratic equation

anonymous · Answer

I get x = 1, -3

rvc · Answer

yep
now put one value at a time in either : y = 2x+1 
or 
y=-x^2+4

anonymous · Answer

Thank you :)

rvc · Answer

Thank you 
All the best :)