Question

2 calcule o valor numerico dos expressoes

a) a²+b²/2 para a =1 b=-2

b) ab+c/ab-c para a=2b=5 c =3

c) a+b3 + 2 a/5 para a=1 b = -7

d) x/2 - y/a + a²/4 para x=-10y = 8-a=2​

Answer 1

Resposta:

Explicação passo-a-passo:

a) $\frac{a^{2}+b^{2}}{2}=\frac{1^{2}+(-2)^{2}}{2}=\frac{1+4}{2}=\frac{5}{2}$

b) $\frac{ab+c}{ab-c}=\frac{2.5+3}{2.5-3}=\frac{13}{7}$

c) $a+3b+2\frac{a}{5}=1+3(-7)+2\frac{1}{5}=1-21+\frac{2}{5}=-20+\frac{2}{5}=\frac{-100+2}{5}=-\frac{98}{5}$

d) $\frac{x}{2}-\frac{y}{a}+\frac{a^{2}}{4}$

para x = -10y = 8 - a = 2. Assim:

x = 2

-10y = 2 => $y=-\frac{2}{10}=>y=-\frac{1}{5}$

8 - a = 2 => -a = 2 - 8 => -a = -6 => a = 6. Portanto:

$\frac{x}{2}-\frac{y}{a}+\frac{a^{2}}{4}=\frac{2}{2}-\frac{(-\frac{1}{5})}{6}+\frac{6^{2}}{4}=1+\frac{1}{30}+\frac{36}{4}=1+\frac{1}{30}+9=\frac{90+3+810}{90}=\frac{903}{90}=\frac{301}{10}$