Download App

Combinations — Maths STD 11 Science — Question

CBSE BoardEnglish MediumSTD 11 ScienceMathsCombinations3 Marks
Question
If $^{18}C_x =\ ^{18}C_{x+2},$ Find $x.$
✓

Answer

We have, If $^nC_p =\ ^nC_q = n$
Then $p + q = n$
Also,$^{18}C_x =\ ^{18}C_{x+2}$
$\Rightarrow x + x + 2 = 18 2x + 2$
$= 18 2x = 18 - 2 2x$
$= 16 x$
$= 8$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Combinations→Combinations — all question types→Maths STD 11 Science question papers→CBSE Board STD 11 Science question papers→CBSE Board question paper generator→

Similar questions

Three consecutive vertices of a parallelogram ABCD are A(6, -2, 4), B(2, 4, -8), C(-2, 2, 4). Find the coordinates of the fourth vertex.
[Hint: Diagonals of a parallelogram have the same mid-point.]
→
Find the distance of the point (2, 5) from the line 3x + y + 4 = 0 measured parallel to a line having slope $\frac{3}{4}.$
→
Find the magnitude, in radians and degrees, of the interior angle of a regular.
Pentagon
→
Find the mean deviation about the mean of the distribution:
Size
$20$
$21$
$22$
$23$
$24$
Frequency
$6$
$4$
$5$
$1$
$4$
→
If $x - iy = \sqrt {\frac{{a - ib}}{{c - id}}} $ prove that ${({x^2} + {y^2})^2} = \frac{{{a^2} + {b^2}}}{{{c^2} + {d^2}}}$
→
Find the equation of that hyperbola whose latus rectum is 8 and conjugate axis is half of distance between foci.
→
Find the value of x for which the points (x, -1), (2, 1) and (4, 5) are collinear.
→
In a $\triangle\text{ABC},$ Prove that:
$\cos\Big(\frac{\text{A+B}}{2}\Big)=\sin\frac{\text{C}}{2}$
→
Evaluate the following limit:
$\lim\limits_{\text{x}\rightarrow{\frac{\pi}{2}}}\frac{\sqrt{2}-\sqrt{1+\sin\text{x}}}{\cos^2\text{x}}$
→
Find the equation of the circle which touches the both axes in first quadrant and whose radius is a.
→