Explicație pas cu pas:
-4x²+25=0
-4x²=0-25=-25
x²= -25:(-4)
x²=6,25
x=±radical din 6,25
x=±2,5=>S={-2,5;2,5}
Succes!
Ecuația de gradul 2 se scrie:
[tex]-4x^2 + 25 =0[/tex]
[tex]- 4x^2 = -25 \Rightarrow 4x^2 = 25 \Rightarrow x^2 = \dfrac{25}{4}[/tex]
[tex]x^2 = \bigg(\dfrac{5}{2}\bigg)^2 \Rightarrow |x| = \pm\dfrac{5}{2}[/tex]
[tex]\Rightarrow S = \bigg\{-\dfrac{5}{2}; \dfrac{5}{2}\bigg\}[/tex]
______
sau:
[tex]-(2x)^2 + 5^2 = 0 \implies (5 - 2x)(5 + 2x) = 0[/tex]
[tex]5 - 2x = 0 \implies x = \dfrac{5}{2}[/tex]
[tex]5 + 2x = 0 \implies x = -\dfrac{5}{2}[/tex]
