Trắc nghiệm Toán 9 (Có đáp án) : Rút gọn biểu thức chứa căn

A.  5 − $2\sqrt{5}$

B. 4

C. 5 + $2\sqrt{5}$

D. 1

A. $2\sqrt{2}$

B. 0

C. $2\sqrt{5}$

D. $\sqrt{2}$

A.  3 + $4\sqrt{2}$

B. 4

C. 2

D. $4\sqrt{2}$

A. 1

B. 0

C. 2

D. 3

A. $\sqrt{5}$

B. $-5\sqrt{5}$

C. $10\sqrt{5}$

D. $5\sqrt{5}$

A. $16\sqrt{a}+12\sqrt{3}$

B. $15\sqrt{3}$

C. $12\sqrt{3}$

D. $16\sqrt{2}$

A. $\sqrt{a}$

B. 4 $\sqrt{a}$

C. 2 $\sqrt{a}$

D. − $\sqrt{a}$

A. $\frac{47}{10}\sqrt{a}$

B. $\frac{21}{5}\sqrt{a}$

C. $\frac{47}{10}\sqrt{2a}$

D. $\frac{47}{5}\sqrt{2a}$

A. 4

B. 5

C. 2

D. 3

A. 6

B. 5

C. 2

D. 3

A. 6

B. 4

C. 2

D. 3

A. $14\sqrt{a}+a\sqrt{a}$

B. $14\sqrt{a}-a\sqrt{a}$

C. $14\sqrt{a}+2a\sqrt{a}$

D. $20\sqrt{a}-2a\sqrt{a}$

A. $66\sqrt{2a}$

B. $52\sqrt{2a}$

C. $54\sqrt{a}$

D. $54\sqrt{2a}$

A. $\frac{a-b}{b^2}\sqrt{\frac{a^2{b}^4}{a^2-2ab+b^2}}=a$ với $a-b>\mathrm{0,}b\ne 0$

B. $\frac{a-b}{b^2}\sqrt{\frac{a^2{b}^4}{a^2-2ab+b^2}}=\left(a\right)$ với a – b > 0, b $\ne$ 0

C. $\frac{a-b}{b^2}\sqrt{\frac{a^2{b}^4}{a^2-2\mathrm{ab}+b^4}}=\mathrm{ab}$ với a – b > 0, b $\ne$ 0

D. $\frac{a-b}{b^2}\sqrt{\frac{a^2{b}^4}{a^2-2\mathrm{ab}+b^4}}=a-b$ với a – b > 0, b $\ne$ 0

A. $\frac{a\sqrt{b}+b\sqrt{a}}{\sqrt{\mathrm{ab}}}+\frac{a-b}{\sqrt{a}+\sqrt{b}}=2\sqrt{a}$

B. $\frac{a\sqrt{b}+b\sqrt{a}}{\sqrt{\mathrm{ab}}}+\frac{a-b}{\sqrt{a}+\sqrt{b}}=\sqrt{a}$

C. $\frac{a\sqrt{b}+b\sqrt{a}}{\sqrt{\mathrm{ab}}}+\frac{a-b}{\sqrt{a}+\sqrt{b}}=2$

D. $\frac{a\sqrt{b}+b\sqrt{a}}{\sqrt{\mathrm{ab}}}+\frac{a-b}{\sqrt{a}+\sqrt{b}}=2\sqrt{b}$

A. $(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}).\left(\frac{-a}{\sqrt{6}}\right)=\frac{-3a}{2}$

B. $(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}).\left(\frac{-a}{\sqrt{6}}\right)=\frac{3a}{2}$

C. $(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}).\left(\frac{-a}{\sqrt{6}}\right)=\frac{-a}{2}$

D. $(\frac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\frac{\sqrt{216}}{3}).\left(\frac{-a}{\sqrt{6}}\right)=\frac{a}{2}$

A. $\left(\frac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right)$ $:\frac{1}{a\left(\sqrt{7}-\sqrt{5}\right)}=2a$

B. $\left(\frac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right)$ $:\frac{1}{a\left(\sqrt{7}-\sqrt{5}\right)}=\frac{2}{a}$

C. $\left(\frac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right)$ $:\frac{1}{a\left(\sqrt{7}-\sqrt{5}\right)}=-2a$

D. $\left(\frac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\frac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right)$ $:\frac{1}{a\left(\sqrt{7}-\sqrt{5}\right)}=\frac{-a}{2}$

A. $\frac{9}{2}$

B. $\frac{9}{4}$

C. 9

D. 18

A. 4

B. 2

C. −2

D. $\frac{2}{3}$

A. 4

B. 2

C. 3

D. 1

A. 5+ $\sqrt{5}$

B. 5

C. $\frac{5+\sqrt{5}}{5}$

D. $\sqrt{5}$

A. 4 + 3 $\sqrt{2}$

B. 4 − 3 $\sqrt{2}$

C. 3

D. 3 $\sqrt{2}$

A. $-\frac{1}{2}$

B. $\sqrt{2}$

C. −1

D. Không tồn tại giá trị P

A. P > 4

B. P < 4

C. P = 4

D. P $\le$ 4