- #1
kreshnik
- 5
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Homework Statement
How should be the value of a so quadratic equation [tex]ax^2-4x+4=0[/tex] to have double solutions?
[tex]A)\;\;2[/tex]
[tex]B)\;\;1[/tex]
[tex]C)\;-1[/tex]
[tex]D)\;-2[/tex]
Homework Equations
The Attempt at a Solution
[tex]D=b^2-4ac[/tex]
If:
[tex]D>0\;\;\rightarrow\; {x_1,x_2}\;\rightarrow\;\text{double solutions.}[/tex]
[tex]D=0\;\;\rightarrow\; {x_1}\;\rightarrow\;\text{only one solution}[/tex]
[tex]D<0\;\;\rightarrow\; \text{no solution.}[/tex]
so:
[tex](-4)^2-4*a*4=16-16*a[/tex]
[tex]\text{If:}\;\;a=-1\;\;\rightarrow\;D=32[/tex]
[tex]\text{If:}\;\;a=-2\;\;\rightarrow\;D=48[/tex]
Which one should be?? thank you.