Question

if x = 1 is a common root of the equation aX square + ax + 3 = 0 and X square + X + b equals to zero then ab=?

Answer 1

Subxtituting the value of x in ax^2 + ax + 3=0,

= a(1)^2 + a(1) + 3=0

= a + a + 3 = 0

2a = -3

a = -3/2...........(1)

Substitute the value of x in x^2 + x + b = 0,

= 1^2 + 1 + b=0

1 + 1 + b =0

2 + b = 0

b = -2..............(2)

Multiplying (1) and (2)

ab = -3/2 * -2

ab = 3

Answer 2

putting the value 1in eq

2a+3=0
a=-3/2

1+1+b=0
b=-2

ab=-3/2 x -2 = 3