E:15694: Difference between revisions

Latest revision as of 17:50, 17 July 2024

E:15694 (Traian Covaciu)

Suma a două numere naturale nenule este 2020. Dacă împărţim primul număr la al doilea, obţinem câtul egal cu restul. Aflaţi cele două numere.

Soluție.

Dacă Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle a} şi Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle b} sunt cele două numere, Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle a > b} şi Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c} este câtul şi restul, atunci Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle a + b = 2020} Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle (1)} şi $a=b\cdot c+c$ $(2)$ , cu Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c < b} .

Înlocuind pe Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle (2)} în Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle (1)} avem Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle b \cdot c + c + b = 2020} , ceea ce conduce la Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c(b + 1) + b + 1 = 2021} , de unde se obțineFailed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle (b + 1)(c + 1) = 2021.} Cum Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 2021 = 43 \cdot 47} putem avea Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle b + 1 = 43} şi Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c + 1 = 47} sau Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle b + 1 = 47} şi Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c + 1 = 43} .

În primul caz avem Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle b = 42} şi Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c = 46 } , care nu convine (avem condiţia Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c < b} ). În al doilea caz avem Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle b = 46} şi Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c = 42} . Obţinem Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle a = 1974} .

Deci, numerele căutate sunt Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle a=1974, b=46.}

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 Dacă <math>a</math> şi <math>b</math> sunt cele două numere, <math>a > b</math> şi <math>c</math> este câtul şi restul, atunci <math>a + b = 2020</math> <math>(1)</math> şi <math>a = b \cdot c + c</math> <math>(2)</math>, cu <math>c < b</math>.
-Înlocuind pe <math>(2)</math> în <math>(1)</math> avem <math>b \cdot c + c + b = 2020</math>, ceea ce conduce la <math>c(b + 1) + b + 1 = 2021</math>, de unde se obține<math display="block">(b + 1)(c + 1) = 2021.</math>Cum <math>2021 = 43 \cdot 47</math> putem avea <math>b + 1 = 43</math> şi <math>c + 1 = 47</math> sau <math>b + 1 = 47</math> şi <math>c + 1 = 43</math>. În primul caz <math>b = 42</math> şi <math>c = 46</math>, care nu convine (avem condiţia <math>c < b</math>). În al doilea caz <math>b = 46</math> şi <math>c = 42</math>. Obţinem <math>a = 1974</math>.
+Înlocuind pe <math>(2)</math> în <math>(1)</math> avem <math>b \cdot c + c + b = 2020</math>, ceea ce conduce la <math>c(b + 1) + b + 1 = 2021</math>, de unde se obține<math display="block">(b + 1)(c + 1) = 2021.</math>
+Cum <math> 2021 = 43 \cdot 47</math> putem avea <math> b + 1 = 43</math> şi <math>c + 1 = 47</math> sau <math>b + 1 = 47</math> şi <math>c + 1 = 43</math>.
+În primul caz avem <math>b = 42</math> şi <math> c = 46 </math>, care nu convine (avem condiţia <math>c < b</math>).
+În al doilea caz avem <math>b = 46</math> şi <math>c = 42</math>. Obţinem <math>a = 1974</math>.
-Deci, numerele căutate sunt<math display="block">a=1974, b=46.</math>
+Deci, numerele căutate sunt <math display="block">a=1974, b=46.</math>