Question

find the value of a such that x-4 is a factor of 5x- 7x- ax -8​

Answer 1

Answer:

x-4 so substitute x = 4 in the equation

5(4)-7(4)-a(4)-8 = 0

20-28-4a-8=0

-8-8-4a=0

-16-4a=0

-4a=16

a=16/-4

a=4

Answer 2

For (x-4) to be a factor if f(x)=5x^2—7x—ax—8
f(4) = 0 {using remainder theorem}
=> 5(4^2) - 7(4) - a(4) - 8 = 0
=> 80 - 28 - 4a - 8 = 0
=> 4a = 80 - 36 = 44
=> a = 11