Question

va rog este urgent dau coroana!
$log_{5}(x {}^{2} + 4x + 7) = log_{5}3$
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Answer 1

Răspuns:

Explicație pas cu pas:

log5(x^2 + 4x + 7) = log5(3)

x^2 + 4x + 7 = 3

x^2 + 4x + 7 - 3 = 0

x^2 + 4x + 4 = 0

a = 1

b = 4

c = 4

∆ = b^2 - 4ac = 4^2 - 4 × 1 × 4 = 16 - 16 = 0 x1 = x2 = -b/2a = -4/2 = - 2

Answer 2

$\it log_5(x^2+4x+7)=log_53 \Rightarrow x^2+4x+7=3 \Rightarrow x^2+4x+4+3=3 \Rightarrow \\ \\ \Rightarrow (x+2)^2+3=3\Big|_{-3} \Rightarrow (x+2)^2=0 \Rightarrow x+2=0 \Rightarrow x=-2$