expression in quadratic form, algebra homework help

1) Write the expression in quadratic form, if possible.
a8 + 10a2 – 16

a) (a4)2 + 10(a2) – 16

b) (a2)2 + 10(a2) – 16

c) a2[(a2)2 + 10(a)] – 16

d) cannot be written in quadratic form

2) Write the expression in quadratic form, if possible.

7b5 – 4b3 + 2b

a) 7(b3)2 - 4(b3) + 2b

b) b[7(b2)2 - 4(b2) + 2]

c) 7(b2)3 - 4(b)3 + 2(b)

d) cannot be written in quadratic form.