Question

if one root of equation2x^2-8x-m=0is 5/2 then find the value of m

Answer 1

p(5/2) = 2(5/2)^2 - 8*5/2 - m = 0
= 2*25/4 - 4*5 - m = 0
= 25/2 - 20 - m = 0
= 25/2 -40/2 - m = 0
= -15/2 - m = 0
= - m = 15/2
therefore m = -15/2