![\"\"](\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2012\/10\/penseinumero.jpg\" "\\"N\u00famero\\"")
<\/a>Qual \u00e9 o n\u00famero?<\/p><\/div>\n
<\/a>Qual \u00e9 o n\u00famero?<\/p><\/div>\n
\u00ad<\/p>\n
| Pensei num n\u00famero<\/td>\n | <\/td>\n | $A$<\/td>\n<\/tr>\n |
| adicionei-lhe $30$<\/td>\n | <\/td>\n | $A + 30$<\/td>\n<\/tr>\n |
| dividi o resultado por $-5$<\/td>\n | <\/td>\n | $\\left( {A + 30} \\right) \\div \\left( { – 5} \\right)$<\/td>\n<\/tr>\n |
| e obtive $16$<\/td>\n | <\/td>\n | $\\left( {A + 30} \\right) \\div \\left( { – 5} \\right) = 16$<\/td>\n<\/tr>\n |
| Em que n\u00famero pensei?<\/td>\n | <\/td>\n | $A = ?$<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Pretendemos determinar o valor de $A$ que\u00a0verifica a igualdade: \u00a0$\\left( {A + 30} \\right) \\div \\left( { – 5} \\right) = 16$.<\/p>\n Tendo em considera\u00e7\u00e3o que a multiplica\u00e7\u00e3o \u00e9 a opera\u00e7\u00e3o inversa da divis\u00e3o e que a subtra\u00e7\u00e3o \u00e9 a opera\u00e7\u00e3o inversa da adi\u00e7\u00e3o, vem:<\/p>\n $$\\begin{array}{*{20}{c}} \u00a0 {\\left( {A + 30} \\right) \\div \\left( { – 5} \\right) = 16} \\\\ \u00a0 {\\left( {A + 30} \\right) = \\left( { – 5} \\right) \\times 16} \\\\ \u00a0 {A + 30 =\u00a0 – 80} \\\\ \u00a0 {A =\u00a0 – 80 – 30} \\\\ \u00a0 {A =\u00a0 – 110} \\end{array} $$<\/p>\n Portanto, a menina pensou no n\u00famero $-110$.<\/p><\/p>\n |