Answer:
[tex]-80[/tex]
Step-by-step explanation:
Use binomial expansion formula:
[tex](a+b)^n=a^n+C^n_1a^{n-1}b^1+C_2^na^{n-2}b^2+...+b^n[/tex]
In your case,
[tex](2x-1)^5=\\ \\=(2x)^5+C^5_1(2x)^4(-1)^1+C^5_2(2x)^3(-1)^2+C^5_3(2x)^2(-1)^3+C^5_4(2x)^1(-1)^4+(-1)^5[/tex]
Find the term containing [tex]x^4[/tex]:
[tex]C^5_1(2x)^4(-1)^1=\dfrac{5!}{1!(5-1)!}\cdot 16x^4\cdot (-1)=-5\cdot 16x^4=-80x^4[/tex]
