Homework Help: check my precalc

Posted by rebekah on Monday, October 1, 2012 at 9:53pm.

#1. solve x^2-1<0 I got (-1,1)

#2 x(x+1) >20
I got (-infinity, -4) U (5,infinity)

#3
what is the domain of this function? f(x)= squre root of (x-3x^2)
i got [-1/3,0]

thanks!!!

check my precalc - Reiny, Monday, October 1, 2012 at 10:06pm
#1
correct

for #2
x^2 + x - 20 > 0
(x+5)(x-4) > 0
critical values are -5 and +4
In my notation it would be
x < -5 OR x > 4

Your (-infinity, -4) U (5,infinity) should then be
(-infinity, -5) U (4,infinity)

#3
correct
check my precalc - rebekah, Tuesday, October 2, 2012 at 6:55am
Thanks so much!

Answer this Question

Related Questions

Algebra - please check my answers. thanxs! Solve the polynomial inequality and ...
Inequality - please check my answers. thanxs! Solve the polynomial inequality ...
BC Calculus - lim x ->infinity (e^x/lnx) I got infinity/0 but is that ...
Check my precalc - 1. find without a calc log base 5 of cubed root of 25. I got ...
Check my precalc? - #1: f(x) = x^2-4x find vrtex, axis ofsym, y-int, x-int if ...
Algebra - Solve x(x-7)(x-9)<0 and express the solution set in interval ...
Calculus - Find the horizontal asymptote of f(x)=e^x - x lim x->infinity...
Algebra - Can you please check my answers? Solve the rational inequality and ...
MATH - I have been trying to do this problem for a couple of days but i cant ...
Rational Inequities - Can you please check my answers? Solve the rational ...

For Further Reading

First Name:
School Subject:
Answer: