question_answer

If\[\alpha \]and\[\beta \]are the roots of the quadratic equation\[2{{x}^{2}}+5x+k=0\]and\[{{\alpha }^{2}}+{{\beta }^{2}}+\alpha \beta =\frac{21}{4},\]then the value of k is:

A)  1             

B)  2

C)  6             

D)  7