MCQ
A rationalising factor of $\frac{1}{\sqrt{9}-\sqrt{7}}$ is
- A$\sqrt{9}+7$
- B$9+\sqrt{7}$
- ✓$3+\sqrt{7}$
- D$3-\sqrt{7}$
✓
Answer
Correct option: C.
$3+\sqrt{7}$
(c)
We know that a rationalising factor of $\sqrt{a} \pm \sqrt{b}$ is $\sqrt{a} \mp \sqrt{b}$. So, a rationalising factor of $\sqrt{9}-\sqrt{7}$ is $\sqrt{9}+\sqrt{7}=3+\sqrt{7}$.
We know that a rationalising factor of $\sqrt{a} \pm \sqrt{b}$ is $\sqrt{a} \mp \sqrt{b}$. So, a rationalising factor of $\sqrt{9}-\sqrt{7}$ is $\sqrt{9}+\sqrt{7}=3+\sqrt{7}$.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Euclid stated that all right angles are equal to each other in the form of:
If a spherical balloon grows to twice its radius when inflated, then the ratio of the volume of the inflated balloon to the original balloon is:
If $\sqrt{5}=2.236,$ then $\frac{1}{\sqrt{5}}.$
→Write the correct answer in the following: The mean of $25$ observations is $36$. Out of these observations if the mean of first $13$ observations is $32$ and that of the last $13$ observations is $40$, the $13^{th}$ observation is:
→Vertical cross-section of a right circular cylinder is always a.
$AOB$ is the diameter of the circle. If $\angle\text{AOE}=150^\circ,$ then the measure of $\angle\text{CBE}$ is: 
→If $\text{x}+\frac{1}{\text{x}}=5,$ then $\text{x}^2+\frac{1}{\text{x}^2}=$
→The sides of a triangle are $7\ cm, 9\ cm$ and $14\ cm.$ Its area is:
→In a bar graph if 1 cm represents 30 km , then the length of bar needed to represent 75 km is
Choose the rational number which does not lie between $-\frac{2}{3}$ and $-\frac{1}{5}.$
→