1.

If the circles `x^2+y^2-9=0`and `x^2+y^2+2a x+2y+1=0`touch each other, then `alpha`is`-4/3`(b) 0(c) 1 (d)`4/3`A. `-4//3`B. 0C. 1D. `4//3`

Answer» Correct Answer - 1,4
The equation of the radical axis is
`2 alpha x +2y+10=0`
i.e., `alpha x +y+5=0` (i)
Putting the value of y from (i) in the circle `x^(2)+y^(2)=9`, we get
`(1+alpha^(2))x^(2)+10 alpha x +16 =0`
Radical axis is trangent . So,
`D=0`
or `36alpha^(2)-64=0`
or `alpha = +- (4)/(3)`


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