Question

quando a=b=-2,determine o valor numerico da expressao algebrica (a-b)(a+b)+ab³-a/b²

Answer 1

$(a-b).(a+b)+ab^3-\frac{a}{b^2}~=\\\\\\=~(-2-(-2))\,.\,(-2+(-2))\,+\,-2\,.\,(-2)^3\,-\,\frac{-2}{(-2)^2}\\\\\\=~(-2+2)\,.\,(-2-2)\,+\,(-2)^4\,-\,\frac{1}{(-2)^{2-1}}\\\\\\=~0\,.\,(-4)~+~16~-~\frac{1}{(-2)^1}\\\\\\=~0~+~16~-~\frac{1}{-2}\\\\\\=~16+\frac{1}{2}\\\\\\=~\frac{2\,.\,16~+~1\,.\,1}{2}\\\\\\=~\frac{32~+~1}{2}\\\\\\=~\boxed{\frac{33}{2}~~ou~~16,5}$