Toán Lớp 9: tính gtbt:
4/( √5-2) – 4/( √5+2)
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Toán Lớp 9: tính gtbt:
4/( √5-2) – 4/( √5+2)
Comments ( 2 )
= $\dfrac{4(\sqrt{5}+2)-4(\sqrt{5}-2)}{(\sqrt{5}-2)(\sqrt{5}+2)}$
= $\dfrac{4\sqrt{5}+8-4\sqrt{5}+8}{5-4}$
= 16
= $\dfrac{4(\sqrt{5}+2)-4(\sqrt{5}-2)}{(\sqrt{5}-2)(\sqrt{5}+2)}$
= $\dfrac{4\sqrt{5}+8-4\sqrt{5}+8}{5-4}$
= 16