Precalculus
posted by Jake on .
Could someone help/verify these answers~
Thanky you!
1.What is the range of the reciprocal function of f(x)=10x^2?
a) {YERy≥1/10}
b) {YERy≥10}
c) {YER1/10≤y<0}
d) YERy<0 or y≥1/10}
Answer: D?

2. It takes Franc 2 hours longer than jane to carpet a certain type of room. Together they can carpet that type of room in 1 7/8 hours. How long would it take for Frank to do the job alone?
a) 1 1/4 hours
b) 3 3/4 hours
c) 3 hours
d) 5 hours

4. Solve 4x/x2 = 3x2/x2 for x.
a) x= 1/2
b) x= 2, 2
c) x= 2
d) x=2
Answer: B

5. How many solutions does this equation (x+5)/(x3)1/x = 4/(x^23x) have?
a) 0
b) 1
c) 2
d) 3
Answer: C

6. The inequality 3x2<(x+4)/(x2) is equivalent to which of the following?
a) 3x^2  9x + 8<0
b) (3x^29x+8)/(x2)<0
c) 3x^29x>0
d) (3x^2  9x)/(x2)<0
Answer: D


1.
y = 10  x^2
x = sqrt(10y)
domain: y <= 10
I don't see that as a choice.
2.
1/f + 1/j = 15/8
but f = j+2
1/(j+2) + 1/j = 15/8
8(j + j+2) = 15j(j+2)
16j + 16 = 15j^2 + 30j
15j^2 + 14j  16 = 0
(3j2)(5j+8) = 0
j = 2/3
so, f = 2 2/3
I don't see that as a choice.
4.
The answer is C, not B because 1/(x2) is not defined.
5. C correct
6. D correct 
For number 4, I got this answer after calculating...
4x/(x2)=(3x2)/(x2)
4x(x2)=(3x2)(x2)
4x^2  8x = 3x^2  6x  2x + 4
4x^23x^28x+6x+2x4=0
x^2  4 =0
(x2)(x+2)=0
x= 2, 2
Am I doing something wrong? 
Yes. 2 is not allowed as a solution, since putting it into the original equation gives
4x/(x2)=(3x2)/(x2)
48/0 = 10/0 
make that
4/0 = 10/0