Find the fourteenth term of ${(3 - a)}^{15}$ .

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Solution

The $r^{t h}$ term in expansion of $(a + x)^{n}$ is given by $^{n} C_{r - 1} a^{n + 1 - r} x^{r - 1}$
$∴$ The fourteenth term in the expansion of $(3 - a)^{15}$ will be $^{15} C_{3} (3)^{2} (- a)^{13} =^{15} C_{2} \times (- 9 a^{13})$
We get the fourteenth term equal to $- 945 a^{13}$

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Find the fourteenth term of (3−a)15.

The rth term in expansion of (a+x)n is given by nCr−1an+1−rxr−1∴ The fourteenth term in the expansion of (3−a)15 will be 15C3(3)2(−a)13=15C2×(−9a13)We get the fourteenth term equal to −945a13

Find the fourteenth term of ${(3 - a)}^{15}$ .

The $r^{t h}$ term in expansion of $(a + x)^{n}$ is given by $^{n} C_{r - 1} a^{n + 1 - r} x^{r - 1}$
$∴$ The fourteenth term in the expansion of $(3 - a)^{15}$ will be $^{15} C_{3} (3)^{2} (- a)^{13} =^{15} C_{2} \times (- 9 a^{13})$
We get the fourteenth term equal to $- 945 a^{13}$