Find the number of real solutions to the system y = x^2 - 5, x^2 + y^2 = 25.
so we get y=4 and x=3since the only integer for x^2+y^2=25 is 3,4,5 since √25=5 and by the pythagorean theorem either x or y=3 or 4 but to be specific we must check and ony 4=3^2-5 works so x=3 , y=4
We can actually solve the equation to see how many real solutions there are.
{y=x2−5x2+y2=25x2+(x2−5)2=25x4−9x2=0x2=0 or x2=9x=−3,0,3
Plugging in these values into the equation gives
y=4,−5,4
in this order.
Therefore there are 3 pairs of real solution, namely (−3,4),(0,−5), and (3,4)