In the xy plane,at what points does graph of y =(x+a)(x+b)

[its.ur.life]

In the xy plane,at what points does the graph of y =(x+a)(x+b) intersect at x axis?
1. a+b =-1
2. The graph intersects the y axis at (0,-6).

1. St 1 is alone suff & not 2
2. St 2 is alone suff & not 1
3. Both 1 & 2 together
4. Each alone is suff.
5. 1& 2 together not sufficient

Ans is 3.

Sol.
It intersects x axis at x=-a and -b
and when i solve for a and b using both statements.
The value comes to be
a = 2 & b =-3
or a=-3 & b=2.

Is my approach and ans correct ?

[jlucero]

Perfect answer and method. Well done.

[its.ur.life]

Thanks :)

[RonPurewal]

Thanks :)

yep.
the key realization is that you don't have to designate which number is "a" and which is "b", as long as you actually have the two numbers.
if you think that you actually have to decide which of 2 and -3 is "a" and which is "b", then you'll mistakenly tihnk that the answer to this problem is (e).