a,\(A=4-2.\left(\dfrac{1}{2}\right)^2+\left(-1\right)^3=\dfrac{5}{2}\)
b, Bậc: 3
\(\text{a)Thay }x=4;y=\dfrac{1}{2};z=-1\text{ vào biểu thức A,ta được:}\)
\(A=4-2.\left(\dfrac{1}{2}\right)^2+\left(-1\right)^3\)
\(A=4-2.\dfrac{1}{4}+\left(-1\right)\)
\(A=4-\dfrac{1}{2}+\left(-1\right)\)
\(A=\dfrac{7}{2}+\left(-1\right)=\dfrac{5}{2}\)
\(\text{b)Bậc là:3}\)