Question

determine o valor numérico de cada expressão​

Answer 1

$\Large\boxed{\begin{array}{l}\rm a)\\\sf\dfrac{a^2-2^a}{\sqrt{a}}\bigg|_{a=4}=\dfrac{4^2-2^4}{\sqrt{4}}\\\\\sf=\dfrac{16-16}{2}=\dfrac{0}{2}=0\checkmark\end{array}}$

$\Large\boxed{\begin{array}{l}\rm b)\\\sf m^2-2mn+n^2=(m-n)^2\\\sf m^2-2mn+n^2\bigg|_{m=1~~n=\dfrac{1}{4}}=(m-n)^2\bigg|_{ m=1~~n=\dfrac{1}{4}}\\\\\sf =\bigg(1-\dfrac{1}{4}\bigg)^2=\bigg(\dfrac{4-1}{4}\bigg)^2\\\\\sf=\bigg(\dfrac{3}{4}\bigg)^2=\dfrac{9}{16}\checkmark\end{array}}$

$\Large\boxed{\begin{array}{l}\rm c)\\\sf\sqrt{\dfrac{a^2+ax}{m}}\bigg|_{a=8,m=9,x=10}\\\sf=\sqrt{\dfrac{8^2+8\cdot10}{9}}=\sqrt{\dfrac{64+80}{9}}\\\\\sf=\sqrt{\dfrac{144}{9}}=\dfrac{12}{3}=4\checkmark\end{array}}$

$\Large\boxed{\begin{array}{l}\sf3(x^2-y^2)-10(x+y)(x-y)\bigg|_{x=-2~y=-2}\\\sf=3\cdot([-2]^2-[-2]^2)-10(-2+[-2])(-2-[-2])\\\\\sf=3(4-4)-10(-2-2)(-2+2)=0\checkmark\end{array}}$