JEE Main · MathematicsMedium

$If the sum of the coefficients in the expansion of (x - 2 y + 3 z)^{n} is 128, then find the value of n .$

A. $5$
B. $6$
C. $7$
D. $8$

Show correct answer & step-by-step solution

Correct answer: C — $7$

Solution

The sum of coefficients is found by setting all variables equal to 1 . Thus, (1 - 2 + 3)^{n} = 2^{n} = 128 . Since 128 = 2^{7}, n = 7 .

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