Given a = - 1 / 3, find the value of - 3 (2a-3a ^ 3 = 5) - 5 (3 / 5a-9 / 10A ^ 3 = 3)

Given a = - 1 / 3, find the value of - 3 (2a-3a ^ 3 = 5) - 5 (3 / 5a-9 / 10A ^ 3 = 3)

-3（2a-3a^3+5）-5（3/5a-9/10a^3+3)
=-6a+9a^3-15-3a+9/2a^3-15
=-9a+27/2a^3-30
=3-1/2-30
=-55/2

Given a ^ 2 + 3a-1 = 0, find the value of 3A ^ 2 + 10A ^ 2 + 2005
Find 3A ^ 3 + 10A ^ 2 + 2005

Because a ^ 2 + 3a-1 = 0, that is, a ^ 2 + 3A = 1
So 3A ^ 3 + 10A ^ 2 + 2005 = 3A ^ 3 + 9A ^ 2 + A ^ 2 + 2005
=3a(a^2+3a)+a^2+2005
=a^2+3a+2005
=2006

If a = - 2 / 3, B = - 4, then the value of | 3a | - | B | / 2 is

When a = - 2 / 3, B = - 4,
|3a|-|b|/2
=2-2
=0