How can I solve for U2 in this equation?

[manal950]

http://store2.up-00.com/June12/Pdb64021.jpg

I will try



391.4368 + 24.264U2 + 2.2332 / 0.8 = 30.5764/1
24.461 = 391.436+24.2564U2 + 12.232

24.461 - 391.436 - 12.232 = 24.2564U2
U2 = (24.461 - 391.436 - 12.232 ) / 24.2564
U2 = 15.6

 

[Borek]

Don't ignore parentheses.

You already made a mistake in your first step. Where did you got 2.2332 from?

 

[manal950]

391.4368 + 24.264U2 / 0.8 + (15.290U2) = 30.5764

Now what will I do

and this next ..

391.4368 + 24.264U2 + 2.2332 / 0.8 = 30.5764/1

 

[Borek]

Don't ignore parentheses. 391.4368 + 24.264U2 / 0.8 and (391.4368 + 24.264U2) / 0.8 are two different things.

Apart from lack of parentheses your first step looks OK now. But I still don't know where did you got 2.2332 from.

$$\frac{a+b}c = \frac a c + \frac b c$$

 

[manal950]

391.4368 + 24.264U2 / 0.8 + (15.290U2) = 30.5764

391.4368 + 24.264U2 + (15.290U2) /0.8= 30.5764

now Is this step is correct ?

 

[Borek]

No, it is wrong. You can't move expressions at random, there are strict rules that you need to follow.

You are still ignoring parentheses, you are wasting your time and my time.

 

[vela]

Don't ignore parentheses.

You already made a mistake in your first step. Where did you got 2.2332 from?

I think the 2.2332 is supposed to be 12.232, which is what you get by multiplying 15.290 by 0.8.

 

[manal950]

So now is my answer is correct or not ... ??

 

[vela]

It's kind of hard to follow what you did, so I'd have to say "probably not." First, take the sage Borek's advice and use parentheses. As he noted, a+b/c means something completely different from (a+b)/c. Don't make others guess what you mean when you can write it in a way that's perfectly clear.

So you're starting off with

30.581((12.8+0.8u₂)/0.8) + 15.290u₂ = 30.5764.

Now show us one step at a time what you're doing. It might help if you explained in words that you're doing each step as well.

 

[manal950]

30.581((12.8+0.8u2)/0.8) + 15.290u2 = 30.5764.

Now I will multiply 30.581 X ((12.8+0.8u2) / 0.8

= 91.4368 + 24.4648U2 /0.8 + 15.290u2 = 30.5764.

now I will bring 91.4368 other side
24.4648U2 /0.8 + 15.290u2 = 30.5764 - 91.4368
24.4648U2 /0.8 + 15.290u2 = -60.8604
now I will apply this rule a+b/c to left side
24.4648U2 + 15.290u2 /0.8 = -60.8604
Now
-60.8604 (0.8) = 24.4648U2 + 15.290u2
u2 = -9.6

Note : U2 the 2 is not square

 

[vela]

30.581((12.8+0.8u2)/0.8) + 15.290u2 = 30.5764.

Now I will multiply 30.581 X ((12.8+0.8u2) / 0.8

= 91.4368 + 24.4648U2 /0.8 + 15.290u2 = 30.5764.

How did you get
$$91.4368 + \frac{24.4648u_2}{0.8} + 15.290u_2 = 30.5764?$$

 

[Borek]

I think I know what is going on. You don't ignore parentheses - you have no idea they are necessary. You are consistently making the same error, which suggests you think (1+2)/3=1+2/3. That's incorrect. (1+2)/3=1/3+2/3. Each expression from the sum in the numerator must be divided separately.