Elišča's 5549

"My daughter will be x years old in x²," said Elišča's father in 1991 at her birthday party.

a) When will the said event occur, and how old will Eliška be at that time?
b) In what year was Eliška born?
c) How old was Eliška in 1991?

Correct answer:

a =  2025
a₂ =  45
b =  1980
c =  11

Step-by-step explanation:

$$\begin{gathered} o=\sqrt{1991}=\sqrt{1991}\doteq 44.6206 \\ {x}_1=44^2=1936 \\ {x}_2=45^2=2025 \\ {x}_3=46^2=2116 \\ a=x_2=2025 \end{gathered}$$

$a_2=\sqrt{x_2}=\sqrt{2025}=45$

$b=a-a_2=2025-45=1980$

$c=1991-b=1991-1980=11$

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