(Multiply all by 3 )
7x+x=3+5x
8x=3+5x
3x=3
x=1
Answer:
x = 6/7, y = 1/2
Step-by-step explanation:
7x + 2y = 7
-14x + 2y = -11
1) 7x + 2y = 7
2y = 7 - 7x
2) -14x + 2y = -11
-14x + 7 - 7x = -11
- 21x = -11-7
- 21x = - 18
x = 18/21 = 6/7
3) 2y = 7 - 7x = 7 - 7*(6/7) = 7 - 6 = 1
2y = 1
y = 1/2
Answer:
x=2
Step-by-step explanation:
Here what we need is that the ratios be equal, which is:
x:(5/2) = 8:10 or, what is the same:
x/(5/2) = 8/10
Lets pick the left term x/(5/2) and multiply both numerator and denominator by 2 to eliminate the fraction on the denominator:
2x/2(5/2) = 2x/5
Now, we would like to make a 10 appear on the denominator. As we already have a five we need to multiply numerator and denominator by the num that, multiplied by 5 gives as 10, this is 2:
2(2x)/2(5) = 4x / 10
So, we transformed x/(5/2) in 4x/10, and both are the same, so we can replace it on our first equation:
4x/10 = 8/10
As both denominators are equal, we can concentrate only in numerators:
4x = 8
Dividing both sides by 4:
x = 2
So, for x=2 both ratios are equivalents.
A 33 gram sample has k value of .1124
(Actually I think the problem SHOULD be worded: A 33 gram sample has k value of -.1124/days)
See attached graphic:
Half-Life = ln (.5) / k
Half-Life = -.693147 / -.1124/days
Half-Life =
<span>
<span>
<span>
6.1667882562
</span>
</span>
</span>
days
Source:
http://www.1728.org/halflif2.htm
Answer:
20%
Step-by-step explanation:
3/15 x 100
= 100/5
= 20% Ans
Hope I made it in time
