Question

find the equation if a + b = - 4 and ab = 5

Answer 1

if a+b = -4
=> a = -4-b------------(i)
=> subs. a in in ab=5
(-4-b)b =5
=> -4b-b^2-5=0
-(b^2 + 4b + 5) = 0
=> b^2 + 5b - b + 5 =0
=> b( b-5) -1 ( b-5)
=> (b-5)(b-1)
therefore b= 5, 1.