Find the coefficient of x^3 in the expansion of (3x + 2)^5

Answer 1

From the Binomial Theorem the 3rd term of (a + b)^5 is 10(a^3)(b^2)

The 10 comes from the Combination Coefficient 5C2 being (5x4)/(1x2)

So we have 10(3x)^3(2)^2. = 10(27x^3)(4) = 1080x^3