b=-8 and b=1/5.
Answer:
Solution given:
5b²+39b=8
5b²+39b-8=0
try to do middle term factorization.
it needs 40 while multiplication and 39 when subtraction.
it is 40-1 and 40*1
now
doing middle term factorization
5b²+(40-1)b-8=0
5b²+40-b-8=0
take common from each 2 term
5b(b+8)-1(b+8)=0
again take common and keep remaining in another brackets
(b+8)(5b-1)=0
either
b=-8
or
b=1/5
