This is a geometric sequence because each term is a constant multiple, called the common ratio, of the previous term. In this case the common ratio, noted as "r", is:
8/-2=-32/8=128/-32=r=-4
The first term is -2
Any geometric sequence can be expressed as:
a(n)=ar^(n-1), a=initial term, r=common ratio, n=term number.
Since we know r and a for this problem already we can say:
a(n)=-2(-4)^(n-1)
Answer:
15 mL of the solution with 20% water will be needed.
Step-by-step explanation:
Use the inverse relationship
10 mL * (18-15)% = x mL * (20-18)%
x = 10 mL * (3/2) = 15 mL
We know that y is equal to x-2. We can just substitute x-2 for y since y is equal to it.
10x- 9(x-2)=24
Distribute.
10x- 9x+18= 24
x+18= 24
Subtract 18 on both sides.
x= 6
Now, plug in x.
y= (6)-2
y= 4
We can check this to see if this works:
4= 6-2, 4=4
10(6)- 9(4)= 24
60-36= 24, 24=24
x=6 and y=4
I hope this helps!
<em>~kaikers</em>
0.333 repeating is the answer :)