Please help solve these problems:
1. If the sides of a square are lengthened bt 5cm, the area becomes 169cm2. Find the length of a side of the original square.
2. 4b2 + 49 - 28b =
3. 28b2 + 196 bt + 343t2 (factor completely)
4. Solve 25x4 - 25x2 + 6 = 0
5. Solve x2 + 6x - 4 = 0