SOLUTION: what is the domain of the function f(x)=sqrt of x^2-3x-10?

Question 255552: what is the domain of the function f(x)=sqrt of x^2-3x-10?
Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
y=sqrt of x^2-3x-10
x^2-3x-10 cannot be negative because the sqrt of a negative number is not real.
So x^2-3x-10>=0
x^2-3x-10=0
(x-5)(x+2)=0
x=5, x=-2
Now we have to test on either side of 5 and -2 to see when y is >=0
x=-5: y=25+15-10=30
x=0: y=-10
x=10 y=100-30-10=60
.
Domain is X (-infinity, -2] U [5,infinity)
.
Ed
.

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