Find the interval for b such thtat the equation has a t least one real solution.

i. X^2+bx-6=0
ii. 2X^2+bx-7=0
iii. x^2+bx+3=0
iv. 3x^2+bx+5

what, no ideas? Check the discriminant.

ax^2+bx+c has only complex roots if b^2-4ac < 0