Question

the coefficient of 'x' in the expansion (x+5)³ is______​

Answer 1

To find :

coefficient of x in (x+5)³

Identity to be used :

to expand the expression , we will use the Identity:

• (a+b)³ = a³+b³+3ab²+3a²b

Solution:

using the Identity above stated :

(x+5)³ = (x)³+(5)³+3(x)(5)²+3(x)²(5)

= x³+125+3x(25)+15x²

= x³+125+75x+15x²

so, there is only single x in the expression.

hence, coefficient of x is 75 .