Question

If 1 is a root of the equations ay² + ay + 3 = 0 and y² + y + b = 0 then ab equals: ?

पर्याय

• A. 3

• B. `-7/2`

• C. 6

• D. −3

Answer 1

The given equations are ay² + ay + 3 = 0 and y² + y + b = 0

Given, 1 is the root of both the equations.

∴ y = 1 will satisfy both these equations.

Putting y = 1 in ay² + ay + 3 = 0, we get

∴`axx(1)^2+axx1+3=0` 

⇒`a+a+3=0` 

⇒`2a+3=0` 

⇒`a=-3/2` ...........(1)

Putting y = 1 in y² + y + b = 0, we get

∴`(1)^2+1+b=0` 

⇒`1+1+b=0` 

⇒`b+2=0` 

⇒`b=-2` ...............(2)

∴`ab=(-3/2)xx(-2)=3` [Using (1)&(2)].

Thus, the value of ab is 3.

Hence, the correct answer is A.