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Ex 11 dau coroanaaaaa

Ex 11 Dau Coroanaaaaa class=

Răspuns :

(a-1)x² + 7x + a = 0
x= - 3
(a-1)(-3)² + 7(-3) + a = 0
(a-1)·9 + (-21) + a = 0
9a-9-21+a = 0
10a-30 = 0
10(a-3) = 0
=> a-3 = 0
a = 3 ∈ R