Question

If the sum of the coefficients in the expansion of $(l^2{x}^2-2lx+1{)}^{50}$ vanishes then $l$ is equal to:

• A. $-1$
• B. $-2$
• C. $1$
• D. $2$

Answer 1

The correct option is C $1$

${(l^2{x}^2-2lx+1)}^{50}$=$(lx-1{)}^{100}$

If the sum of the coefficcents of the expansion vanishes mens equal to 0

means on putting x=1

$\Rightarrow$$lx-1=0$

$\Rightarrow$$l-1=0$

$\Rightarrow$$l=1$