( a-4)²-2a(5a-4) =-⅓

To solve the given expression, we can simplify it step by step:

(a-4)² - 2a(5a-4)

Expanding (a-4)² using the formula (a-b)² = a² - 2ab + b²:

= a² - 8a + 16 - 2a(5a-4)

Expanding the product of -2a and (5a-4):

= a² - 8a + 16 - 10a² + 8a

Combining like terms:

= -9a² + 8a² - 8a + 8a + 16

Simplifying:

= -a² + 16

Since no further simplification is possible, the expression (-a² + 16) cannot be equal to -⅓. Thus, it seems there is an error or typo in either the question or the answer given.