# Algebra again

1. Sep 29, 2005

### DB

can some 1 give me a hand with this? thanks
$$\frac{150}{v+20}+\frac{150}{v-5}=3.5$$

2. Sep 29, 2005

### Leong

1. make the denominator the same.
2. cross multiply the equation to get rid of the fraction form.

3. Sep 29, 2005

### DB

i get the -65 n 80 which i think is right so thanks leong

4. Sep 29, 2005

### Leong

5. Sep 29, 2005

### DB

80 works, -65 doesnt

6. Sep 29, 2005

### DB

it came down to:
$$3.5v^2+52.5v-650$$

7. Sep 30, 2005

### VietDao29

Uhmmm, I think you should check your calculation again.
Here we go:
$$\frac{150}{v + 20} + \frac{150}{v - 5} = 3.5$$
Multiply both sides by (v + 20) (v - 5)
$$\Leftrightarrow (v + 20)(v - 5)\left(\frac{150}{v + 20} + \frac{150}{v - 5}\right) = 3.5(v + 20)(v - 5)$$
$$\Leftrightarrow 150(v - 5) + 150(v + 20) = 3.5(v ^ 2 + 15v - 100)$$
$$\Leftrightarrow 300v + 2250 = 3.5v ^ 2 + 52.5v - 350$$
$$\Leftrightarrow ...$$
Can you go from here?
By the way, it does not come down to 3.5v2 + 52.5v - 650 = 0.
Viet Dao,