Question

calcule as equacoes incompletas ...d) x2-4=0 e)x2-9=0 f)x2-81=0

Answer 1

Isole a variável:

$d)~ x^{2} -4=0\to~~ x^{2} =4\to ~~x=\pm \sqrt{4} \to~~x=\pm~2\\\\\\ S=\{-2;2\}\\\\\\\\\\ e)~ x^{2} -9=0\to ~~ x^{2} =9\to ~~x=\pm \sqrt{9} \to~~x=\pm~3\\\\\\S=\{-3;3\}\\\\\\\\\\ f)~ x^{2} -81=0\to~~ x^{2} =81\to~~x=\pm \sqrt{81} \to x=\pm~9\\\\\\S=\{-9;9\}$

Answer 2

d-) 
x² - 4 = 
x² = 4
x = (+ - )√4
x = (+ - ) 2
Solução; x = -2 ou x = 2
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x² - 9 = 0 
x² = 9 
x = (+ -)√9
x = (+ - ) 3
Solução: x = -3 ou x = 3
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x² - 81 = 0
x² = 81
x = (+ - ) √81
x = ( + -) 9
Solução:x = - 9 ou x = 9