Bạn tham khảo:
1.(trang số 2)
a/
A=$\sqrt{7-4\sqrt{3}}$ +$\sqrt{9+6\sqrt{3}+3}$
= $\sqrt{4-4\sqrt{3}+3}$+$\sqrt{(3+\sqrt{3})^2}$
=$\sqrt{(}2+\sqrt{3})^2$+$\sqrt{(3+\sqrt{3})^2}$
= 2-$\sqrt{3}$+3+ $\sqrt{3}$
= 5
B=($\frac{3\sqrt{x}+6}{x-4}$+ $\frac{\sqrt{x}}{\sqrt{x}-2}$): $\frac{x-9}{\sqrt{x}-3}$
B=($\frac{3(\sqrt{x}+2)}{(\sqrt{x}-2)(\sqrt{x}+2}$+ $\frac{\sqrt{x}}{\sqrt{x}-2}$):$\frac{(\sqrt{x}-3)(\sqrt{x}+3)}{\sqrt{x}-3}$
B=($\frac{3}{\sqrt{x}-2}$+ $\frac{\sqrt{x}}{\sqrt{x}-2}$):$\sqrt{x}+3$
B=$\frac{3+\sqrt{x}}{\sqrt{x}-2}$ .$\frac{1}{\sqrt{x}+3}$
B=$\frac{1}{\sqrt{x}-2}$
b/Với A=B
⇔5=$\frac{1}{\sqrt{x}-2}$
⇔5$\sqrt{x}$ -10=1
⇔5$\sqrt{x}$ =11
⇔x=4,84
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