HI! HERE ARE THE SOLUTIONS:
1> 25a to the fourth - 14 a squared b to the fourth + b to the eight
= 25 a to the fourth - 10 a squared b to the fourth + b to the eight -
4 a squared b to the fourth
= square of (5 a squared -b to the fourth) - square of (2ab squared )
= ( 5 a2 + 2ab2 - b4)(5a2 - 2ab2 - b4)
2> 3a4 + 48b4 - 36a2b2
= 3(a4 - 12a2b2 + 16b4)
= 3 { a4 -8a2b2 + 16b4 - 4a2b2}
= 3 { ( a2-4b2)2 - (2ab)2
= 3 { (a2 -2ab -4b2)(a2 +2ab - 4b2)
= 3 (a2-2ab -4b2)(a2 + 2ab - 4b2)

got it!!!