solve 4 x: (x-1)(x+1)??plz?

Question

here is my oreginal proplem
0.4=(Q-200/-20)*(120/(Q+200)
solve for Q
i need this for my economic class and i forgot the basics of maths
so any help is very welcomed

Answer 1

This is an expression and it isn't equated to anything... best I can do is expand it out using FOIL method:

First: x * x = x²
Outer: x * 1 = x
Inner: -1 * x = -x
Last: -1 * 1 = -1

Adding them up:
x² + x - x - 1

The x terms cancel:
x² - 1

Note: this is called a difference of squares. Recognize it so you can go backwards.

Edit, for your revised question:
.......... (Q - 200) ...... 120
0.4 = -------------- x ------------
.............. -20 .........(Q + 200)

Multiply across:
..........120 (Q - 200)
0.4 = --------------------
...........-20 (Q + 200)

Cancel -20 from top and bottom:
..........-6 (Q - 200)
0.4 = -----------------
...........(Q + 200)

Multiply both sides by (Q + 200):
0.4(Q + 200) = -6(Q - 200)

Expand out:
0.4Q + 80 = -6Q + 1200

Add 6Q to both sides:
6.4Q + 80 = 1200

Subtract 80 from both sides:
6.4Q = 1120

Divide both sides by 6.4:
Q = 1120 / 6.4
Q = 175

Answer 2

Simplify:
= (x - 1)(x + 1)
= x^2 + x - x - 1
= x^2 - 1

Finding values of x:
(x - 1)(x + 1) = 0
x - 1 = 0, x = 1
x + 1= 0, x = - 1

Answer: x = 1, - 1

Answer 3

Simplifying
(x + -1)(x + 1)

Reorder the terms:
(-1 + x)(x + 1)

Reorder the terms:
(-1 + x)(1 + x)

Multiply (-1 + x) * (1 + x)
(-1(1 + x) + x(1 + x))
((1 * -1 + x * -1) + x(1 + x))
((-1 + -1x) + x(1 + x))
(-1 + -1x + (1 * x + x * x))
(-1 + -1x + (1x + x2))

Combine like terms: -1x + 1x = 0
(-1 + 0 + x2)
(-1 + x2)

Factor a difference between two squares.
(1 + x)(-1 + x)

Final result:
(1 + x)(-1 + x)

Answer 4

It has to be equal to something in order for you to solve for x. Or do you mean expand?

(x-1)(x+1)=x^2-1

Answer 5

x= or x=-1 assuming its all eaqual 0