Question

resolva a expressão numérica:
7÷8×9-29+10÷20​

Answer 1

Resposta:

7÷8×9-29+10÷20

(7/8) * 9 - 29 +10/20

63/8 -29 +1/2

63/8 -29*8/8 +4*1/(2*4)

= 63/8 - 232/8 + 4/8

=(63-232+4)/8  =-165/8

Answer 2

$7\div 8\cdot 9-29+10\div 20\\ \frac{7}{8}\cdot \:9-29+\frac{10}{20}\\ \frac{7}{8}\cdot \:9=\frac{63}{8}\\ \frac{7}{8}\cdot \:9\\ \mathrm{Multiplicar\:fracoes}:\quad \:a\cdot \frac{b}{c}=\frac{a\:\cdot \:b}{c}\\ =\frac{7\cdot \:9}{8}\\ \mathrm{Multiplicar\:os\:numeros:}\:7\cdot \:9=63\\ =\frac{63}{8}$

$\frac{10}{20}=\frac{1}{2}\\ \frac{10}{20}\\ \mathrm{Eliminar\:o\:fator\:comum:}\:10\\ =\frac{1}{2}\\ =\frac{63}{8}-29+\frac{1}{2}\\ \mathrm{Converter\:para\:fracao}:\quad \:29=\frac{29}{1}\\ =-\frac{29}{1}+\frac{1}{2}+\frac{63}{8}\\ \mathrm{Minimo\:multiplo\:comum\:de\:}1,\:2,\:8:\quad 8\\\\  1,\:2,\:8\\ \mathrm{Calcular\:um\:numero\:composto\:por\:fatores\:que\:aparecam\:ao\:menos\:em\:algum\:dos\:seguintes:}\\ =2\cdot \:2\cdot \:2\\ \mathrm{Multiplicar\:os\:numeros:}\:2\cdot \:2\cdot \:2=8\\ =8$

$\mathrm{Reescrever\:as\:fracoes\:baseando-se\:no\:minimo\:mutiplo\:comum}\\ =-\frac{232}{8}+\frac{4}{8}+\frac{63}{8}\\ \mathrm{Ja\:que\:os\:denominadores\:sao\:iguais,\:combinar\:as\:fracoes}:\quad \frac{a}{c}\pm \frac{b}{c}=\frac{a\pm \:b}{c}\\ =\frac{-232+4+63}{8}\\ \mathrm{Somar/subtrair:}\:-232+4+63=-165\\ \mathrm{Aplicar\:as\:propriedades\:das\:fracoes}:\quad \frac{-a}{b}=-\frac{a}{b}\\ =-\frac{165}{8}$

$\left(\mathrm{Decimal:\quad }\:-20.625\right)$