Question

(k-3)(k+3)-(2+k)² при k = -2,5.

Answer 1

(k-3)(k+3)-(2+k)²=(k²-9)-(4+4k+k²)=k²-9-4-4k-k²=-4k-13
k=-2,5 , -4.(-2,5)-13=10-13=-3

Answer 2

-2.5-3-2.5+3-4+5=--5+5-3+3-4=-4

Answer 3

To evaluate the expression (k-3)(k+3) - (2+k)² for k = -2.5, we substitute -2.5 in place of k in the expression and perform the calculations.

Let's calculate step by step:

1. Substitute k = -2.5 into (k-3)(k+3): (-2.5 - 3)(-2.5 + 3) = (-5.5)(0.5) = -2.75

2. Substitute k = -2.5 into (2+k)²: (2 + (-2.5))² = (2 - 2.5)² = (-0.5)² = 0.25

3. Subtract the result of step 2 from the result of step 1: -2.75 - 0.25 = -3

Therefore, when k = -2.5, the expression (k-3)(k+3) - (2+k)² evaluates to -3.