To Find : coefficient of x5
For (1+x)3
a=1, b=x and n=3
We have a formula,
By using this formula, we get, ×
Coefficients of x5 are
x0 .x5 = 1× (-6)=-6
x1 .x4 = 3×15=45
x2 .x3 = 3×(-20)=-60
x3 .x2 = 1×15=15
Therefore, Coefficients of x5 = -6+45-60+15 = -6
Conclusion : Coefficients of x5 = -6