Question

Answer 1

Thay x = -2 ta được:

\(2.\left(-2\right)^2+4.\left(-2\right)+5\\ =2.4+\left(-8\right)+5\\ =8+\left(-8\right)+5=0+5=5\)

Answer 2

Thay vô là 
2.(-2)^2+4.(-2)+5
=2.4+(-8)+5
=8+(-8)+5
=0+5
=5

 

Answer 3

2.(-2)\(^2\) +4.(-2)+5
= 2.4+(-8)+5
= 8+(-8)+5
= 0+5
= 5

Answer 4

5