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True or False ? Please Justify/ Explain you answer . 10 points best answer?
Is (X +2)^3 = x^3 -4 a quadratic equation .
6 Answers
- 7 years ago
(generally) there are 3 types of statements.
1) TRUE statement
2) FALSE statement
3) OPEN statement
For example, a FALSE statement would be
x + 1 = x - 4
because you know that it is FALSE for any
value of x, since when you subtract x from
both sides you a statement " 1 = -4 "
and thus you know that it is for sure FALSE.
A TRUE statement would, for example be,
g² + 3 = g² + 3
since you see that what is basically says is,
" a number = a number ", and you know that
it is true, just like 1=1 r=r 3=3 -6=-6
and on... is true, (right?)
In other words, whatever number you plug in
for g into g² + 3 = g² + 3, the sides will
always be equal to each other.
An OPEN statement however, would be something like,
w + 3 = 2w - 1
Here, you get a statement that is OPEN,
because you can solve the equation and
find what "w" equals.
Solution:
w + 3 = 2w - 1
add 1 to both sides
w + 3 = 2w - 1
+ 1 + 1
───────────
w + 4 = 2w
(the 1 on the right side has canceled)
Now, subtract w from both sides
w + 4 = 2w
- w - w
───────────
4 = w
and hence, you know that
w + 3 = 2w - 1
is true when w is 4
but false for any other values.
This statement, that can be solved for the variable
to find what the variable equals (to make the statement true)
is called an OPEN statement.
Source(s): ▒ No sources ▒ - Demiurge42Lv 77 years ago
You're not making much sense. Statements are true or false. Questions are not true or false.
"Is (X +2)^3 = x^3 -4 a quadratic equation?" is a question not a statement. Therefore it makes no sense to ask if it is true or false.
(X +2)^3 = x^3 -4 is a quadratic equation because it can be written in the form ax^2+bx+c = 0.
- 6 years ago
no
(x + 2)^3 = (x + 2)(x + 2)(x + 2)
= (x + 2)(x^2 + 4x + 4)
= x^3 + 6x^2 + 12x + 8
in general this is not the same as x^3 - 4
therefore false
- GlippLv 77 years ago
no
(x + 2)^3 = (x + 2)(x + 2)(x + 2)
= (x + 2)(x^2 + 4x + 4)
= x^3 + 6x^2 + 12x + 8
in general this is not the same as x^3 - 4
it may be the same if 6x^2 + 12x + 8 = -4
or 6x^2 + 12x + 12 = 0
=> x^2 + 2x + 2 = 0
=> (x + 1)^2 = -1
=> x + 1 = ±i
=> x = -1 ± i
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