Animated Solution for Mathematics - Binomial Theorem: The maximum value of the term independent of 't' in the expansion of (tx1/5+t(1−x)1/10)10 where x∈(0,1) is:
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Visualized Solution
General Term Tr+1
General term of (a+b)n is Tr+1=(rn)an−rbr
Here, n=10, a=tx1/5, and b=t(1−x)1/10
Substituting Values
Tr+1=(r10)(tx1/5)10−r(t(1−x)1/10)r
Isolating the Power of t
Separate the powers of t: Tr+1=(r10)t10−r(x1/5)10−r(1−x)r/10t−r
Combine the t terms: Tr+1=(r10)t10−2rx510−r(1−x)10r
Term Independent of t
For the term independent of t, the exponent of t must be zero.
Set 10−2r=0
Solving for r: 2r=10⟹r=5
The Sixth Term T6
Substitute r=5 into the expression for Tr+1:
T6=(510)t0x510−5(1−x)105
T6=(510)x1(1−x)1/2=(510)x1−x
Defining the Function f(x)
Let f(x)=x1−x for x∈(0,1)
The maximum value of T6 occurs when f(x) is maximum.
T6=(510)f(x)
Differentiating f(x)
Differentiate f(x) using the product rule:
f′(x)=1⋅1−x+x⋅21−x1⋅(−1)
f′(x)=1−x−21−xx
Finding Critical Points
Set f′(x)=0 for maximum value:
1−x−21−xx=0
1−x=21−xx
Value of x for Maximum
Multiply both sides by 21−x:
2(1−x)=x
2−2x=x⟹3x=2
x=32
Calculating Maximum T6
Substitute x=32 into T6:
T6,max=(510)(32)1−32
T6,max=(510)(32)31
T6,max=(510)332
Final Simplified Answer
Using (510)=5!5!10!=(5!)210!
T6,max=(5!)210!⋅332
Final expression: 33(5!)22⋅10!
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The Sigma Insight: General Term and Middle Term
Solution Diagram
The Elegance of Binomial Symmetry
My dear student, welcome to a journey through one of the most beautiful landscapes in algebra: the Binomial Theorem. Today, we are not just solving a problem; we are uncovering the hidden structure within the expression (tx1/5+t(1−x)1/10)10.
It might look like a daunting mess of variables and fractional powers, but I promise you, there is a rhythm to it. Let us peel back the layers together.
Phase 1
The Hunt for the Independent Term
Every binomial expansion is a collection of terms, and the general term Tr+1 is our master key. We know that for any expression (a+b)n, the general term is given by Tr+1=(rn)an−rbr.
In our case, n=10, a=tx1/5, and b=t(1−x)1/10.
When we substitute these into our formula, we get:
Tr+1=(r10)(tx1/5)10−r(t(1−x)1/10)r
Now, here is where the magic happens. We need to isolate the variable t. Let us gather all the t terms together.
From the first part, we have t10−r. From the second part, because t is in the denominator, it brings a t−r into the mix. When we multiply these, we add the exponents: 10−r+(−r)=10−2r.
So, our term becomes:
Tr+1=(r10)t10−2rx510−r(1−x)10r
The question asks for the term independent of t. This is the moment of truth. For a term to be independent of t, the exponent of t must be zero.
Thus, we set 10−2r=0, which immediately gives us r=5. We have found our target!
Phase 2
The Calculus of Optimization
With r=5, our term T6 (the sixth term) simplifies beautifully. Substituting r=5 into our expression, the t term becomes t0=1.
The x terms become x510−5=x1 and (1−x)105=(1−x)1/2. So, we are left with:
T6=(510)x1−x
Now, we enter the realm of calculus. We want to maximize this term. Since (510) is just a constant, we only need to maximize the function f(x)=x1−x for x∈(0,1).
Imagine this curve—it starts at zero, rises to a peak, and falls back to zero at x=1. To find that peak, we find the derivative f′(x) and set it to zero.
Using the product rule, the derivative is:
f′(x)=1⋅1−x+x⋅21−x1⋅(−1)=1−x−21−xx
Setting f′(x)=0 leads us to:
1−x=21−xx
Multiplying both sides by 21−x gives 2(1−x)=x, which simplifies to 2−2x=x, or 3x=2. Thus, the maximum occurs at x=2/3.
Phase 3
The Final Synthesis
We have done the hard work. Now, we simply substitute x=2/3 back into our expression for T6:
Finally, we expand the binomial coefficient (510)=5!5!10!. Putting it all together, we arrive at our final, elegant result:
33(5!)22⋅10!
Look at that! From a complex binomial expression, we navigated through algebra and calculus to find a precise, beautiful constant. This, my friend, is the power of physics and mathematics. You didn't just solve a problem; you mastered a process. Keep that curiosity alive!