If a = 4 and b = -6, what is the value of the expression \(- {a^3} - {a^2}b + 7{b^2} - ab + 9?\)
Explanation
Working through each variable in \(- {a^3} - {a^2}b + 7{b^2} - ab + 9\) :
\(-a^{3}=-4^{3}=-6\)
\(-a^{2} b=-4^{2} \times-6=16 \times-6=-96\)
\(7 b^{2}=7 \times-6^{2}=7 \times 36=252\)
\( -ab = -4 \times -6 = 24\)
\(-64 + -96 + 252 + 24 + 9 = 125\)