For the following quadratic equations, evaluate the discriminant and thus state the number and nature of the roots.
1. x2 − 5x + 6 = 0
9. a2 − 0.5x − 1 = 0
2. x2 − 6x + 9 = 0
10.
3. s2 − 12s + 21 = 0
11. x2 − x = 12
4. p2 + 5p + 16 = 0
12. (y − 5)2 = 0
5. r2 + r − 12 = 0
13. 2r2 -2r + 5 = 0
6. 3y(4y − 5) = 0
14. 20x2 − 19x + 3 = 0
7. x2 − x +10= 0
15. 3t2 + 2t − 6 = 0
8. x2 − 81 = 0
16. (x + 5)2 = 25
