Answer:
[tex] \displaystyle 4320 {x }^{3} [/tex]
Step-by-step explanation:
to solve binomials like this there's a way called binomial theorem given by
[tex] \displaystyle {(a + b)}^{n} = \sum _{k = 0} ^{n} \binom{n}{k} {a}^{n - k} {b}^{k} [/tex]
but for this question we need the following part
[tex] \displaystyle \boxed{ \binom{n}{k} {a}^{n - k} {b}^{k} }[/tex]
from the question we obtain that a,b and n is 3x,4 and 5 since we want to find the coefficient x³ k should be (5-3) = 2 so we have determined the variables now just substitute
[tex] \displaystyle \binom{5}{2} {(3x)}^{5 - 2} \cdot {4}^{2} [/tex]
simplify which yields:
[tex] \displaystyle \boxed{ \bold{4320 {x }^{3}} }[/tex]
and we are done!
