Question

A = x(2y - x) - 2y(z -2y) tại x= 2 ; y=1/2 ; z= -1 tính gt biểu thức 

Answer 1

\(A=2xy-x^2-2yz+4y^2=2\cdot2\cdot\dfrac{1}{2}-2^2-2\cdot\dfrac{1}{2}\cdot\left(-1\right)+4\cdot\left(\dfrac{1}{2}\right)^2\)

\(=2-4+1+4\cdot\dfrac{1}{4}=-2+1+1=0\)

Answer 2

A = 2 (2 . 1/2 - 2) - 2 . 1/2 (-1 - 2 . 1/2) 

A = 2 (1 - 2) - 1 (-1 - 1) 

A = 2 . (-1)  - 1 . (-2) 

A = -2 + 2

A = 0

@Liz.Ald2094

Answer 3

=2⋅2⋅12−22−2⋅12⋅(−1)+4⋅(12)2A=2xy−x2−2yz+4y2=2⋅2⋅12−22−2⋅12⋅(−1)+4⋅(12)2