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If ""^(100)C(6)+4." "^(100)C(7)+6." "^(...

If `""^(100)C_(6)+4." "^(100)C_(7)+6." "^(100)C_(8)+4." "^(100)C_(9)+""^(100)C_(10)` has the value equal to `" "^(x)C_(y)` , then the possible value (s) of `x+y` can be :

A

112

B

114

C

196

D

198

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to evaluate the expression: \[ ^{100}C_6 + 4 \cdot ^{100}C_7 + 6 \cdot ^{100}C_8 + 4 \cdot ^{100}C_9 + ^{100}C_{10} \] and express it in the form \(^{x}C_{y}\). ### Step 1: Group the terms We can group the terms in a way that allows us to use the binomial coefficient identity: \[ ^{n}C_{r} + ^{n}C_{r+1} = ^{n+1}C_{r+1} \] We start by rewriting the expression: \[ ^{100}C_6 + 4 \cdot ^{100}C_7 + 6 \cdot ^{100}C_8 + 4 \cdot ^{100}C_9 + ^{100}C_{10} \] This can be rearranged as: \[ ^{100}C_6 + (4 \cdot ^{100}C_7) + (6 \cdot ^{100}C_8) + (4 \cdot ^{100}C_9) + ^{100}C_{10} \] ### Step 2: Use the binomial coefficient identity We can express \(4 \cdot ^{100}C_7\) as: \[ ^{100}C_7 + ^{100}C_7 + ^{100}C_7 + ^{100}C_7 = 4 \cdot ^{100}C_7 \] This allows us to combine terms: \[ ^{100}C_6 + ^{100}C_7 + ^{100}C_7 + ^{100}C_7 + ^{100}C_7 + 6 \cdot ^{100}C_8 + 4 \cdot ^{100}C_9 + ^{100}C_{10} \] ### Step 3: Combine coefficients Now we can combine the coefficients of \(^{100}C_7\) and \(^{100}C_8\): \[ ^{100}C_6 + 4 \cdot ^{100}C_7 + 6 \cdot ^{100}C_8 + 4 \cdot ^{100}C_9 + ^{100}C_{10} \] This can be rewritten as: \[ ^{100}C_6 + ^{100}C_7 + ^{100}C_7 + ^{100}C_7 + ^{100}C_7 + ^{100}C_8 + ^{100}C_8 + ^{100}C_8 + ^{100}C_8 + ^{100}C_8 + ^{100}C_9 + ^{100}C_9 + ^{100}C_{10} \] ### Step 4: Use the identity repeatedly Now we can use the binomial coefficient identity repeatedly: 1. Combine \(^{100}C_6\) and \(^{100}C_7\): \[ ^{100}C_6 + ^{100}C_7 = ^{101}C_7 \] 2. Combine the next terms: \[ ^{101}C_7 + ^{100}C_8 + ^{100}C_8 + ^{100}C_8 + ^{100}C_8 + ^{100}C_8 = ^{101}C_8 \] 3. Continue this process until we combine all terms. ### Step 5: Final combination After combining all terms, we find that: \[ ^{100}C_6 + 4 \cdot ^{100}C_7 + 6 \cdot ^{100}C_8 + 4 \cdot ^{100}C_9 + ^{100}C_{10} = ^{104}C_{10} \] ### Step 6: Find \(x + y\) Here, \(x = 104\) and \(y = 10\). Thus: \[ x + y = 104 + 10 = 114 \] ### Final Answer The possible value(s) of \(x + y\) can be: \[ \boxed{114} \]
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