a^3*a^4*a+（a^2）^4+（-2a^4）^2
=a^(3+4+1) + a^(2×4) +(-2)^2 ×a^(4×2)
=a^8 + a^8 + 4a^8
=6a^8
-(-2b^2*b)^4
=-(-2)^4 × (b^2)^4 ×b^4
=-16 × b^8×b^4
=-16×b^(8+4)
=-16b^12