### Related Formula textSum of all coefficients in f(x)^n = f(1)^n$\text{Sum of all coefficients in } f(x)^n = f(1)^n$ ### Core Logic To find the sum of all coefficients in a polynomial expansion, substitute the variable x = 1$x = 1$. For A$A$ (Sum of coefficients of (1-3x+10x^2)^n$(1-3x+10x^2)^n$): A = (1 - 3(1) + 10(1)^2)^n$A = (1 - 3(1) + 10(1)^2)^n$ A = (1 - 3 + 10)^n = (8)^n$A = (1 - 3 + 10)^n = (8)^n$ For B$B$ (Sum of coefficients of (1+x^2)^n$(1+x^2)^n$): B = (1 + (1)^2)^n$B = (1 + (1)^2)^n$ B = (1 + 1)^n = (2)^n$B = (1 + 1)^n = (2)^n$ ### Step 1: Establishing the Relation We have A = 8^n$A = 8^n$ and B = 2^n$B = 2^n$. Observe that 8 = 2^3$8 = 2^3$. A = (2^3)^n = (2^n)^3$A = (2^3)^n = (2^n)^3$ Substituting B = 2^n$B = 2^n$ into the expression: A = B^3$A = B^3$ ### Pattern Recognition Summing coefficients of *any* multi-nomial expansion is trivially simple: just plug in x=1$x=1$ (or x=y=z=1$x=y=z=1$ for multivariable expressions). It collapses the variables, leaving only the arithmetic sum of the coefficients. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Binomial Theorem

### Related Formula frac^nC_rr+1 = frac^n+1C_r+1n+1$\frac{^nC_r}{r+1} = \frac{^{n+1}C_{r+1}}{n+1}$ sum_k=0^n ^nC_k = 2^n$\sum_{k=0}^n {^nC_k} = 2^n$ ### Core Logic The given series can be rewritten using summation notation: S = sum_r=1^9 frac^11C_rr+1$S = \sum_{r=1}^{9} \frac{^{11}C_r}{r+1}$ Applying the coefficient shifting identity frac^nC_rr+1 = frac^n+1C_r+1n+1$\frac{^nC_r}{r+1} = \frac{^{n+1}C_{r+1}}{n+1}$: S = sum_r=1^9 frac^12C_r+112$S = \sum_{r=1}^{9} \frac{^{12}C_{r+1}}{12}$ S = frac112 sum_r=1^9 ^12C_r+1$S = \frac{1}{12} \sum_{r=1}^{9} {^{12}C_{r+1}}$ ### Step 1: Expand and Complete the Series Expand the internal sum by shifting the index bounds: S = frac112 left( ^12C_2 + ^12C_3 + dots + ^12C_10 right)$S = \frac{1}{12} \left( ^{12}C_2 + ^{12}C_3 + \dots + ^{12}C_{10} \right)$ We know the complete sum of binomial coefficients for n=12$n=12$ is 2^12$2^{12}$. We just need to subtract the missing boundary terms: k = 0, 1, 11, 12$k = 0, 1, 11, 12$. 2^12 = sum_k=0^12 ^12C_k$2^{12} = \sum_{k=0}^{12} {^{12}C_k}$ The missing terms evaluate to: ^12C_0 = 1$^{12}C_0 = 1$ ^12C_1 = 12$^{12}C_1 = 12$ ^12C_11 = 12$^{12}C_{11} = 12$ ^12C_12 = 1$^{12}C_{12} = 1$ Sum of missing terms = 1 + 12 + 12 + 1 = 26$= 1 + 12 + 12 + 1 = 26$. ### Step 2: Calculate Final Fraction Substitute this back into the series equation: S = frac112 left[ 2^12 - 26 right]$S = \frac{1}{12} \left[ 2^{12} - 26 \right]$ S = frac112 [ 4096 - 26 ]$S = \frac{1}{12} [ 4096 - 26 ]$ S = frac407012$S = \frac{4070}{12}$ Simplify the fraction by dividing by 2 to achieve the coprime structure fracnm$\frac{n}{m}$: S = frac20356$S = \frac{2035}{6}$ Thus, n = 2035$n = 2035$ and m = 6$m = 6$, and they are coprime (gcd(2035, 6) = 1$\gcd(2035, 6) = 1$). Calculate n + m$n + m$: n + m = 2035 + 6 = 2041$n + m = 2035 + 6 = 2041$ ### Pattern Recognition Whenever you see binomial coefficients divided by their sequential index (r+1$r+1$), always use the absorption identity frac1n+1 binomn+1r+1$\frac{1}{n+1} \binom{n+1}{r+1}$ to bump the top index up by 1. Then fill the array to force the complete 2^n+1$2^{n+1}$ sum. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Binomial Theorem

### Related Formula textCoefficient of (r+1)^textth text term in (1+x)^n text is ^nC_r$\text{Coefficient of } (r+1)^{\text{th}} \text{ term in } (1+x)^n \text{ is } {}^nC_r$ ^nC_r + ^nC_r+1 = ^n+1C_r+1$^nC_r + {}^nC_{r+1} = {}^{n+1}C_{r+1}$ ### Core Logic Let the four consecutive binomial coefficients be ^nC_r, ^nC_r+1, ^nC_r+2, ^nC_r+3${}^nC_r, {}^nC_{r+1}, {}^nC_{r+2}, {}^nC_{r+3}$. Given these correspond to 2 - p, p, 2 - alpha, alpha$2 - p, p, 2 - \alpha, \alpha$ respectively. From the properties of combinations: ^nC_r + ^nC_r+1 = (2 - p) + p = 2${}^nC_r + {}^nC_{r+1} = (2 - p) + p = 2$ Rightarrow ^n+1C_r+1 = 2 quad dots(1)$\Rightarrow {}^{n+1}C_{r+1} = 2 \quad \dots(1)$ Similarly: ^nC_r+2 + ^nC_r+3 = (2 - alpha) + alpha = 2${}^nC_{r+2} + {}^nC_{r+3} = (2 - \alpha) + \alpha = 2$ Rightarrow ^n+1C_r+3 = 2 quad dots(2)$\Rightarrow {}^{n+1}C_{r+3} = 2 \quad \dots(2)$ ### Step 1: Identifying the Inconsistency From equations (1) and (2): ^n+1C_r+1 = ^n+1C_r+3 = 2${}^{n+1}C_{r+1} = {}^{n+1}C_{r+3} = 2$ By combination properties, if ^nC_x = ^nC_y${}^nC_x = {}^nC_y$ and x neq y$x \neq y$, then x + y = n$x + y = n$. So, (r+1) + (r+3) = n+1 Rightarrow 2r + 4 = n+1 Rightarrow n = 2r + 3$(r+1) + (r+3) = n+1 \Rightarrow 2r + 4 = n+1 \Rightarrow n = 2r + 3$. Substitute n$n$ back into the equality: ^2r+4C_r+1 = 2${}^{2r+4}C_{r+1} = 2$ The binomial coefficient must be ge 2$\ge 2$. However, for any valid integer r ge 0$r \ge 0$, ^2r+4C_r+1${}^{2r+4}C_{r+1}$ grows very rapidly. Let's test small values: If r = 0$r = 0$, ^4C_1 = 4 neq 2${}^4C_1 = 4 \neq 2$. If r = 1$r = 1$, ^6C_2 = 15 neq 2${}^6C_2 = 15 \neq 2$. Hence, no integer values satisfy this condition, making the given data inherently inconsistent. ### Step 2: Conclusion Due to inconsistent data resulting in a mathematically impossible scenario, this question was treated as a Bonus/Dropped question. ### Pattern Recognition Adding consecutive binomial coefficients yields the sum from Pascal's triangle identity ^nC_r + ^nC_r+1 = ^n+1C_r+1${}^nC_r + {}^nC_{r+1} = {}^{n+1}C_{r+1}$. If identical sums yield small integer invariants like 2, they typically break bounding limits for ^nC_k${}^nC_k$ combinations. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Binomial Theorem

### Related Formula frac^nC_rr+1 = frac^n+1C_r+1n+1$\frac{^nC_r}{r+1} = \frac{^{n+1}C_{r+1}}{n+1}$ sum_k=0^n ^n+1C_k+1 cdot ^nC_n-k = ^2n+1C_n+1$\sum_{k=0}^n {}^{n+1}C_{k+1} \cdot {}^nC_{n-k} = {}^{2n+1}C_{n+1}$ ### Core Logic Simplify alpha$\alpha$ by absorbing the denominator: alpha = sum_k=0^n frac^nC_k cdot ^nC_kk + 1$\alpha = \sum_{k=0}^{n} \frac{{}^nC_k \cdot {}^nC_k}{k + 1}$ Multiply and divide by (n+1)$(n+1)$: alpha = frac1n+1 sum_k=0^n fracn+1k+1 ^nC_k cdot ^nC_n-k$\alpha = \frac{1}{n+1} \sum_{k=0}^{n} \frac{n+1}{k+1} {}^nC_k \cdot {}^nC_{n-k}$ alpha = frac1n+1 sum_k=0^n ^n+1C_k+1 cdot ^nC_n-k$\alpha = \frac{1}{n+1} \sum_{k=0}^{n} {}^{n+1}C_{k+1} \cdot {}^nC_{n-k}$ This corresponds to choosing k+1$k+1$ items from a set of n+1$n+1$, and n-k$n-k$ items from a set of n$n$. Total items chosen = (k+1) + (n-k) = n+1$(k+1) + (n-k) = n+1$ from a total pool of (n+1) + n = 2n+1$(n+1) + n = 2n+1$. alpha = frac1n+1 cdot ^2n+1C_n+1$\alpha = \frac{1}{n+1} \cdot {}^{2n+1}C_{n+1}$ ### Step 1: Evaluating Beta Now for beta$\beta$: beta = sum_k=0^n-1 frac^nC_k cdot ^nC_k+1k + 2$\beta = \sum_{k=0}^{n-1} \frac{{}^nC_k \cdot {}^nC_{k+1}}{k + 2}$ Convert ^nC_k${}^nC_k$ to ^nC_n-k${}^nC_{n-k}$ and absorb the denominator into ^nC_k+1${}^nC_{k+1}$: beta = frac1n+1 sum_k=0^n-1 ^nC_n-k cdot fracn+1k+2 ^nC_k+1$\beta = \frac{1}{n+1} \sum_{k=0}^{n-1} {}^nC_{n-k} \cdot \frac{n+1}{k+2} {}^nC_{k+1}$ beta = frac1n+1 sum_k=0^n-1 ^nC_n-k cdot ^n+1C_k+2$\beta = \frac{1}{n+1} \sum_{k=0}^{n-1} {}^nC_{n-k} \cdot {}^{n+1}C_{k+2}$ Here, total items chosen is (n-k) + (k+2) = n+2$(n-k) + (k+2) = n+2$ from a total pool of n + (n+1) = 2n+1$n + (n+1) = 2n+1$. beta = frac1n+1 cdot ^2n+1C_n+2$\beta = \frac{1}{n+1} \cdot {}^{2n+1}C_{n+2}$ ### Step 2: Applying the Given Ratio Given 5alpha = 6beta Rightarrow fracbetaalpha = frac56$5\alpha = 6\beta \Rightarrow \frac{\beta}{\alpha} = \frac{5}{6}$. fracbetaalpha = fracfrac1n+1 ^2n+1C_n+2frac1n+1 ^2n+1C_n+1 = frac^2n+1C_n+2^2n+1C_n+1$\frac{\beta}{\alpha} = \frac{\frac{1}{n+1} {}^{2n+1}C_{n+2}}{\frac{1}{n+1} {}^{2n+1}C_{n+1}} = \frac{^{2n+1}C_{n+2}}{^{2n+1}C_{n+1}}$ Using the ratio property frac^nC_r^nC_r-1 = fracn-r+1r$\frac{^nC_r}{^nC_{r-1}} = \frac{n-r+1}{r}$: Here, n to 2n+1$n \to 2n+1$ and r to n+2$r \to n+2$. fracbetaalpha = frac2n+1 - (n+2) + 1n+2 = frac2n+1 - n - 2 + 1n+2 = fracnn+2$\frac{\beta}{\alpha} = \frac{2n+1 - (n+2) + 1}{n+2} = \frac{2n+1 - n - 2 + 1}{n+2} = \frac{n}{n+2}$ ### Step 3: Solving for n Equate and solve: fracnn+2 = frac56$\frac{n}{n+2} = \frac{5}{6}$ 6n = 5n + 10 Rightarrow n = 10$6n = 5n + 10 \Rightarrow n = 10$ ### Pattern Recognition Any fractional binomial coefficient like C_k / (k+x)$C_k / (k+x)$ triggers an absorption identity to step up the index. Then, multiplying terms turns into a simple combinatorial Vandermonde convolution. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Binomial Theorem

### Related Formula T_r+1 = binomnr a^n-r b^r$T_{r+1} = \binom{n}{r} a^{n-r} b^r$ ### Core Logic General term in the expansion of left(7^1/2 + 11^1/6right)^824$\left(7^{1/2} + 11^{1/6}\right)^{824}$ is: t_r+1 = binom824r (7)^frac824-r2 (11)^r/6$t_{r+1} = \binom{824}{r} (7)^{\frac{824-r}{2}} (11)^{r/6}$ For the term to be integral, both powers must be integers. This means: 1) frac824 - r2$\frac{824 - r}{2}$ must be an integer, which means r$r$ must be even. 2) fracr6$\frac{r}{6}$ must be an integer, which means r$r$ must be a multiple of 6. Since any multiple of 6 is already even, the condition reduces to: r$r$ must be a multiple of 6. ### Step 1: Finding valid values of r The possible values for r$r$ are 0, 1, 2, dots, 824$0, 1, 2, \dots, 824$. Valid r = 0, 6, 12, dots, 822$r = 0, 6, 12, \dots, 822$. This forms an arithmetic progression with first term a=0$a=0$, common difference d=6$d=6$, and last term L=822$L=822$. L = a + (n-1)d$L = a + (n-1)d$ 822 = 0 + (n-1)6$822 = 0 + (n-1)6$ n - 1 = frac8226 = 137$n - 1 = \frac{822}{6} = 137$ n = 138$n = 138$ Thus, there are 138 integral terms. ### Pattern Recognition Finding rational/integral terms in a binomial expansion strictly requires finding the LCM of the fractional power denominators, then counting multiples up to n$n$. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Binomial Theorem