Question

if x=1 is common root of equations ax2 +ax+3=0and x+x+b=0 then value of ab will be 3

Answer 1

given: x= 1
ax2+ax+3= 0
putting x=1
a+a+3=0
or, 2a+3=0
or, a=(-1.5)
similarly putting x=1 in x+x+b=0
we get,
b=(-2)
so, ab= 3

Answer 2

Answer:

Now We have to prove that

ax² +ax +3=0------- (i)

x+x+b=0----------(ii)

we have to find the value of a and b then their product will give the answer i.e

ab=3

Now Given

x=1.

For equation (i)

ax²+ax+3=

=> a(1)² + a(1) +3=0 [putting the value of x]

=> a+a=-3

=> 2a= -3

=>a = -1.5

Now Putting the value of X in equation (ii) we get

1+1+b=0

=>2+b=0

=> b= -2

Now according to the given problem

ab= -1.5 * - 2

=> ab= 3 [Proved]