What is the solution of 2x - 5x(x-6) = 3.?

Question

I'm helping my friend with her homework, but I completely forgot how to do this!

Yes my friend. But it doesn't really matter, I just need an answer. If it helps you at all, I'll lie and say its mine. And why would I lie anyway? I don't know how to do it either way.

Answer 1

Alright, hers is where the previuos guy left off.

2x - 5x(x - 6) = 3
2x - 5x^2 + 30x = 3
32x - 5x^2 = 3
0 = 5x^2 - 32x + 3
This is in the form
(a)X^2+(b)X+(c)=0

hence,
a=5, b=(-32) and c=3

We have the formula which is a bit complicated

X={(-b)(+/-)B(}/2a

where B=sqrt(b^2-4ac)

using this,
we get
B=31.048349392520047457724923534346
B=(apprx)31.05
hence we get,
X1=(32+31.05)/10=6.305

And

X2=(32-31.05)/10=0.095

Both satisfy the equation only approximately thanks to the approximation of the root.

Peace out.

Answer 2

First get rid of the brackets:

2x - 5x^2 + 30x = 3

rearrange so that you have terms in x^2, x and a constant:

- 5x^2 + 32x - 3 = 0

Then use the quadratic formula with the following values:

a = -5; b = 32; c = -3

I make it that x = - 32 ± √(32^2 - (4 * -5 * -3))/ -10

x = - 32 ± √(32^2 - 60)/ -10

= - 32 ± 31.048349392520047457724923534346 / -10

or 3.2 ± 3.1048349392520047457724923534346

(notice, I changed the sign and divided by 10)

x = 0.095165060747995254227507646566
or x = 6.3048349392520047457724923534346

YUK! (The long numbers are because I copied and pasted from Windows Calculator)

Answer 3

You're gonna need the Quadratic Formula, after you do some distribution of -5x and move the 3 to the other side of the equation. See the link below for help with said formula. (Note: From what I did, the answer is not whole numbers (e.g., 2, 3).)

Answer 4

sure, your "friend". ;)

2x - 5x(x - 6) = 3
2x - 5x^2 + 30x = 3
32x - 5x^2 = 3
0 = 5x^2 - 32x + 3
Looks really ugly from there on. Are you sure you copied the problem right?

At this point you have to resolve to using the ugly quadratic formula. a=5, b=-32, c=3.
x = [-b +/- sqrt(b^2 - 4ac)] / 2a <-- quadratic formula
= [32 +/- sqrt(964)] / 10
= [16 +/- sqrt(241)] / 5
x = approximately 6.305 or 0.095

The person below me said 13. But if you plug in 13, it's not right. You'll get:
2x - 5x(x-6) = 3
26 - 65(7) = 3
-429 = 3
wrong, so x is not 13. :)

Answer 5

13

Answer 6

blue