Do any one of them, please help needed

Answer:
a = -3
Step-by-step explanation:
f(x) = 5x³+4x²+3x-4a
f(-1) = 8
therefore , x = -1
substituting x = -1 in 5x³ + 4x² +3x-4a
5(-1)³ + 4(-1)² + 3(-1) - 4a. = 8
-5 + 4 -3 - 4a = 8
-8 + 4 -4a = 8
-4 - 4a = 8
shifting -4 from LHS to RHS
-4a = 8+4
-4a = 12
[tex] - a = \frac{12}{4} [/tex]
therefore
-a = 3
a = -3
ANS = the value of a = -3
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