X^2+2x-8=0 in simplest radical form

What's the difference between: x≥0 and nonnegative integer. ?

Prove sin2a + cos2a - 1 / sin2a + cos2a + 1 = 1 - tana / 1 + cota

Kevin's bank offered him a 4.5% interest rate for his mortgage. if he purchases 3 points, what will be his new rate?