I'm not sure what your variables are, but I will try task 3 with you.
y=$500(in billions)
x= the number of years that have passed since 2009
percentage of decrease: 1 - % =
so your formula will look like this: y(1 - %)^x
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Answer:
7k
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Step-by-step explanation:
We are trying to combine like terms with the expression: -k - ( - 8k)
We are pretty much solving it.
Solve:
-k - ( - 8k)
The "- ( -" turns into a plus sign.
So it would look like:
-k - -8k or -k + 8k
Now, you would finish solving
-k + 8k = 7k
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Solutions
Factor <span>3x</span>²<span><span>−2x−8</span><span>
</span></span>1. Multiply 3 by -8, which is -24.
2. Ask: Which two numbers add up to -2 and multiply to -24?
3. Answer: 4 and -6
4. Rewrite <span>−2x </span>as the sum of <span>4x </span>and <span>−6x</span>:

<span>
</span><span>Factor out common terms in the first two terms, then in the last two terms
</span>
Factor out the common term <span>3x+4
</span>
Solve for <span>x
</span>1. Ask: When will <span>(3x+4)(x−2) </span>equal zero?
2. Answer: When <span>3x+4=0 </span>or <span>x−2=0.</span>
3. Solve each of the 2 equations above:
x = −<span>4 / 3</span>,<span>2</span>
A₁ = 1; r=1.5
a₉ = a₁ * r⁸ = 1 * 1.5⁸ ≈ 25.63
Answer: c. 25.63