Derek is four times as old as sarah. two years ago the sum of their ages was 36. how old is each now?

1 answer:

4 0

Let's write a system of equations. We will use D for Derek's age and S for Sarah's age:

D = 4S

(D - 2) + (S - 2) = 36

We can simplify the second equation:

D + S - 4 = 36

D + S = 40

Now we can use substitution to plug 4S in for D in the second equation:

(4S) + S = 40

5S = 40

S = 8

Sarah is 8 years old.

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A bag contains 4 oranges, 3 grapefruits, and 8 tangerines. A piece of fruit is chosen from the bag at random. What is the probab

s2008m [1.1K]

What you’ll have to do is find the probability of the oranges and the tangerines. There is a total is 15 fruit. 12 of those are not grapefruit. You’ll then have to find the percentage of 12/15.

12 is divided by 15, then multiplied by 100.

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3 years ago

Read 2 more answers

Rewrite the form In exponential form: Log100 = x

andrey2020 [161]

Answer:

$10^x=100$

Step-by-step explanation:

You know how subtraction is the opposite of addition and division is the opposite of multiplication? A logarithm is the opposite of an exponent. You know how you can rewrite the equation 3 + 2 = 5 as 5 - 3 = 2, or the equation 3 × 2 = 6 as 6 ÷ 3 = 2? This is really useful when one of those numbers on the left is unknown. 3 + _ = 8 can be rewritten as 8 - 3 = _, 4 × _ = 12 can be rewritten as 12 ÷ 4 = _. We get all our knowns on one side and our unknown by itself on the other, and the rest is computation.

We know that $3^2=9$ ; as a logarithm, the exponent gets moved to its own side of the equation, and we write the equation like this: $\log_3{9}=2$ , which you read as "the logarithm base 3 of 9 is 2." You could also read it as "the power you need to raise 3 to to get 9 is 2."

One historical quirk: because we use the decimal system, it's assumed that an expression like $\log1000$ uses base 10, and you'd interpret it as "What power do I raise 10 to to get 1000?"

The expression $\log100=x$ means "the power you need to raise 10 to to get 100 is x," or, rearranging: "10 to the x is equal to 100," which in symbols is $10^x=100$ .