Question

(2a-1) (4a²+2a+1) при a=-1/2

Answer 1

разность кубов

x³ - y³ = (x - y)(x² + xy + y²)

x= 2a

y = 1

(2a-1) (4a²+2a+1) = (2a)³ - 1³ = 8a³ - 1

при a=-1/2

(2*-1/2)³ - 1 = (-1)³ - 1 = -2

Answer 2

To evaluate the expression (2a-1)(4a²+2a+1) when a = -1/2, we substitute -1/2 in place of "a" and simplify the expression.

(2(-1/2)-1)(4(-1/2)²+2(-1/2)+1)

First, let's simplify the terms within the parentheses:

= (-1-1)(4(-1/2)²-1+1) = (-2)(4(1/4)-1+1) = (-2)(1-1+1) = (-2)(1)

Finally, we multiply the two numbers:

= -2

Therefore, when a = -1/2, the expression (2a-1)(4a²+2a+1) evaluates to -2.