[ 4a ]+[ ( 2z/-2-5/a)]
\(4a + \left(\dfrac{2z}{-2}-\dfrac{5}{a}\right)\)
\(=\dfrac{4a^2}{a} -\dfrac{az}{a}-\dfrac{5}{a}\)
\(=\dfrac{4a^2-az-5}{a}\)
- [3y / (-4 - y)] - [(-5y) / (64 - 4y²)]
\(-\dfrac{3y}{-4-y}-\dfrac{-5y}{64-4y^2}\)
\(=\dfrac{3y}{4+y}+\dfrac{5y}{4\cdot(16-y^2)}\)
\(=\dfrac{3y}{4+y}+\dfrac{5y}{4\cdot(4-y)(4+y)}\)
\(=\dfrac{3y\cdot 4\cdot(4-y)}{4\cdot(4-y)(4+y)}+\dfrac{5y}{4\cdot(4-y)(4+y)}\)
\(=\dfrac{3y\cdot 4\cdot(4-y)+5y}{4\cdot(4-y)(4+y)}\)
\(=\dfrac{48y-12y^2+5y}{64-4y^2}\)
\(=\dfrac{53y-12y^2}{64-4y^2}\)