Question

Ajutooor!!

Dacă x+1/x=4, atunci x^2+1/x^2 = ???

Answer 1

Răspuns:

$x+\dfrac{1}{x}=4\Rightarrow\left(x+\dfrac{1}{x}\right)^2=16\Rightarrow x^2+2+\dfrac{1}{x^2}=16\Rightarrow x^2+\dfrac{1}{x^2}=14$

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