Question

Află toate numerele de forma a bcd,daca:
a+b=13
a-b=5
b>d
c=bx2
Va rog repede da-u 30 de puncte si coroana
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Answer 1

$\it n=\overline{abcd}\\ \\ a+b=13\\a-b=5\\ -----\\2a\ \ \ \ =18 \Rightarrow a=9,\ \ b=4\\ \\ c=b\cdot2=4\cdot2=8\\ \\ b>d \Rightarrow 4>d \Rightarrow d<4 \Rightarrow d\in\{0,\ 1,\ 2.\ 3 \}\\ \\ n\in\{9480,\ 9481,\ 9482,\ 9483\}$