What is the sum of the coefficients in the expansion of ( 1 + x ) 5 ?
This problem is posed by Subham B .
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yeh indeed its a pascal 3angle wkwk
yup.. it's easier
Well, according to the binomial theorem, the sum of the coefficients is
k = 0 ∑ 5 ( k 5 ) = 3 2
It's a Newton's Binomial, which can be write how: ( 1 + x ) 5 ) = ∑ k = 1 5 ∗ x n − k ∗ y k ∗ ( k n ) , where n = exponent, a = a, b = b. So, 1 + 5 + 1 0 + 1 0 + 5 + 1 = 3 2
k n need to be the permutation of n and k
n choose k, instead of n/k and then it makes scene.
Use Pascal triangle .Since we have 5 in the exponent,we get 6 terms. So we have to use 6th row of Pascal triangle. Since we have 1 and x ,we can directly add the numbers in the 6th row to get the sum of the coefficients. Sixth row of Pascal triangle is 1 5 10 10 5 1 Their sum =1+5+10+10+5+1 = 32
Let P ( x ) = ( 1 + x ) 5 , so P ( 1 ) is the sum of the coefficients of P ( x ) .
this is simple problem but so hard to find its simple. it use pascal triangle just look at the number of expansion, it's 5. so, 2^5 = 32
5C1+5C2+5C3+5C4+5C5 =1+5+10+10+5+1 =32 topic: Binomial equation, Combination & permutation.
5C0 missing !!!
just make use of pascal triangle so the coefficients will be 1 5 10 10 5 1 so 1+5+10+10+5+1=32
why taking 1+1??
(1+x)^5 = 5C0. X^(5-0) + 5C1. X^(5-1) + 5C2. X^(5-2) + 5C3. X^(5-3) + 5C4. X^(5-4) + 5C5. X^(5-5) = 1x^5 + 5.x^4 + 10x^3 + 10x^2 + 5x + 1. So, sum of all coefficients of (1+x)^5 = 1 + 5 + 10 + 10 + 5 + 1 = 32. Answer : 32
for a polynomial, (1+x)^n, the rth co-efficient is rCn........in current case r wil range from 1 to 5 and n = 5....co-efficients are 1, 5, 10, 10, 5, 1 ( 6 terms).........thus sum is 32
5c0+5c1+5c2+5c3+5c4+5c5 = 32
We use here the binomial theorem to find the expansion of the expression ( 1 + x ) 5 .Also, we must know that the value of the binomial coefficient ( r n ) = r ! × ( n − r ) ! n ! . From the binomial theorem, we know that ---
( 1 + x ) 5 = ( 0 5 ) + ( 1 5 ) x + ( 2 5 ) x 2 + ( 3 5 ) x 3 + ( 4 5 ) x 4 + ( 5 5 ) x 5
Now, Sum of the coefficients = ( 0 5 ) + ( 1 5 ) + ( 2 5 ) + ( 3 5 ) + ( 4 5 ) + ( 5 5 )
= 1 + 5 + 1 0 + 1 0 + 5 + 1 = 3 2
Put x=1 in expansion of (1+x)^n.... You will find that sum of co-efficients is 2^n... Here as n=5, sum of co-efficients is 2^5=32.....
sum C(5,k) , k=0 to 5. Newton Binomial
1, 1 (by pascals triangle)
1, 2, 1
1, 3, 3, 1
1, 4, 6, 4, 1
1, 5, 10, 10, 5 , 1
Therefore, sum of 1+5+10+10+5+1 = 32
by binomial expansion as well
1+5+10+10+5+1 = 32
expansion of (1+x)^5=1+ 5x + 10x^2 + 10x^3 + 5x^4 + x^5 now add every coefficients i.e. 1+5+10+10+5+1
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The series forms PASCAL's traingle
1, 1
1, 2, 1
1, 3, 3, 1
1, 4, 6, 4, 1
1, 5, 10, 10, 5 , 1
Therefore, sum of 1+5+10+10+5+1 = 32