If a = 23 and b = -29 then the value of 25a2 + 40ab + 16b2 is:

Just plug in your numbers:

25a^2 + 40ab + 16b^2
= (5a+4b)^2
= (5*23 - 4*29)^2
= ____

To find the value of 25a^2 + 40ab + 16b^2, substitute the values of a and b into the expression.

Given that a = 23 and b = -29, substitute these values into the expression:
25(23)^2 + 40(23)(-29) + 16(-29)^2

Simplify each term:
25(529) + 40(-667) + 16(841)

Evaluate each term:
13225 - 26680 + 13456

Combine the terms to get the final answer:
13330

Therefore, the value of 25a^2 + 40ab + 16b^2 when a = 23 and b = -29 is 13330.