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2 years ago

2.5 x 10 to the third power times what number is equal to 5 x 10 to the sixth power?

Mathematics

1 answer:

Taya2010 [7]2 years ago

4 0

Answer:

2 is the number because half of 5 is 2.5

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Which figure shows a reflection of pre-image ABC over the y-axis?

bixtya [17]

Answer:

Step-by-step explanation:

Sorry you got it wrong but i was confused since y axis is up and down but they ment straight across

4 0

1 year ago

EVALUATE THE FOLLOWING -15 x 6

Nat2105 [25]

the answer is 90

Step-by-step explanation:

I used a calculator so-

6 0

2 years ago

If a,b,c and d are positive real numbers such that logab=8/9, logbc=-3/4, logcd=2, find the value of logd(abc)

Eva8 [605]

We can expand the logarithm of a product as a sum of logarithms:

$\log_dabc=\log_da+\log_db+\log_dc$

Then using the change of base formula, we can derive the relationship

$\log_xy=\dfrac{\ln y}{\ln x}=\dfrac1{\frac{\ln x}{\ln y}}=\dfrac1{\log_yx}$

This immediately tells us that

$\log_dc=\dfrac1{\log_cd}=\dfrac12$

Notice that none of $a,b,c,d$ can be equal to 1. This is because

$\log_1x=y\implies1^{\log_1x}=1^y\implies x=1$

for any choice of $y$ . This means we can safely do the following without worrying about division by 0.

$\log_db=\dfrac{\ln b}{\ln d}=\dfrac{\frac{\ln b}{\ln c}}{\frac{\ln d}{\ln c}}=\dfrac{\log_cb}{\log_cd}=\dfrac1{\log_bc\log_cd}$

so that

$\log_db=\dfrac1{-\frac34\cdot2}=-\dfrac23$

Similarly,

$\log_da=\dfrac{\ln a}{\ln d}=\dfrac{\frac{\ln a}{\ln b}}{\frac{\ln d}{\ln b}}=\dfrac{\log_ba}{\log_bd}=\dfrac{\log_db}{\log_ab}$

so that

$\log_da=\dfrac{-\frac23}{\frac89}=-\dfrac34$

So we end up with

$\log_dabc=-\dfrac34-\dfrac23+\dfrac12=-\dfrac{11}{12}$

###

Another way to do this:

$\log_ab=\dfrac89\implies a^{8/9}=b\implies a=b^{9/8}$

$\log_bc=-\dfrac34\implies b^{-3/4}=c\implies b=c^{-4/3}$

$\log_cd=2\implies c^2=d\implies\log_dc^2=1\implies\log_dc=\dfrac12$

Then

$abc=(c^{-4/3})^{9/8}c^{-4/3}c=c^{-11/6}$

So we have

$\log_dabc=\log_dc^{-11/6}=-\dfrac{11}6\log_dc=-\dfrac{11}6\cdot\dfrac12=-\dfrac{11}{12}$

4 0

2 years ago

What is 22% of 45<br><br><br><br> what is 32.5% of 250

antoniya [11.8K]

Answer:

22%*45=

(22:100)*45 =

(22*45):100 =

990:100 = 9.9

32.5%*250=

(32.5:100)*250 =

(32.5*250):100 =

8125:100 = 81.25

7 0

1 year ago

Read 2 more answers

Simplify x^2 over x^2 - 2x

Scilla [17]

Answer:

2x^2-2x

Step by Step Explanation:

The 2 x^2 come together to form 2x^2 and since there is no other number that has x but no ^2 -2x stays the same.

8 0

1 year ago