Answer:
6x^2 -29 +35.
Step-by-step explanation:
use the FOIL method(First, Outer,Inner, and Last.)
2x x 3x=6x^2.
2x x -7=-14x.
-5 x 3x =-15x.
-5 x -7=35.
= 6x^2 -14x -15x+35
6x^2 -29x +35.
Answer:
Our number is 7.
Step-by-step explanation:
We also know that it's 2x + 21 = 5x.
Now we solve.
21 = 5x - 2x
21 = 3x
7 = x
This is a relatively simple half life calculation.
To go from 6 to 3 grams, 1622 years is required.
3 to 1.5 grams another 1622 years is required.
So, it undergoes exactly 2 half-lives or 3,244 years.
To see more about half-life click here:
http://www.1728.org/halflife.htm
Answer:
second option
Step-by-step explanation:
Given
+ 6x² + 5 = 0
let u = x², then
u² + 6u + 5 = 0 ← in standard form
(u + 1)(u + 5) = 0 ← in factored form
Equate each factor to zero and solve for u
u + 1 = 0 ⇒ u = - 1
u + 5 = 0 ⇒ u = - 5
Change u back into terms of x, that is
x² = - 1 ( take the square root of both sides )
x = ± 
= ± i ( noting that = i ), and
x² = - 5 ( take the square root of both sides )
x = ± 
= ± 
= ± 
× = ± i
Solutions are x = ± i and x = ± i
