Question 47: Calculate the value of the expression \(\begin{array}{l} B = 84{\left( {{x^2}{y^4}} \right)^2}:14{x^2 }{y^6} = 6{x^2}{y^2} \end{array}\) at \(x = \frac{{ – 3}}{4}\) and y=4.

\(\begin{array}{l} B = 84{\left( {{x^2}{y^4}} \right)^2}:14{x^2}{y^6} = 6{ x^2}{y^2} \end{array}\)

Replace \(x = \frac{{ – 3}}{4}\) and y=4 into B we get \(B = 6. {\left( {\frac{{ – 3}}{4}} \right)^2}{.4^2} = 54\)