Can you please help me -2.5x + 6 + 30x - 4.5

Mathematics

2 answers:

VARVARA [1.3K]3 years ago

7 0

The answer is: 27.5x+1.5

igomit [66]3 years ago

6 0

It is 27.5x+1.5 :) ;;;; I

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Allen has a photo that is 6 in by 8 in. What will the dimensions of the photo be if he scales it down by a factor of ? (5 points

Irina18 [472]

Answer:

It will be 3 in by 4 in

Step-by-step explanation:

Original dimension is 6 in by 8 in

If he scale it down by a factor of 1/2

The new dimension will be

1/2(6) by 1/2(8)

= 3 by 4

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2 years ago

There are 8 tennis players in a round robin tournament, which means each team will play every other team once. How many matches

Aliun [14]

<h3>Answer: 28</h3>

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Explanation:

Method 1

Imagine a table with 8 rows and 8 columns to represent all possible match-ups. You can actually draw out this table or just think of it as a thought experiment.

There are 8*8 = 64 entries in the table. Along the northwest diagonal, we have each team pair up with itself. This is of course silly and impossible. We cross off this entire diagonal so we drop to 64-8 = 56 entries.

Then notice that the lower left corner is a mirror copy of the upper right corner. A match-up like AB is the same as BA. So we must divide by 2 to get 56/2 = 28 different matches.

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Method 2

There are 8 selections for the first slot, and 8-1 = 7 selections for the second slot. We have 8*7 = 56 permutations and 56/2 = 28 combinations.

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Method 3

Use the nCr combination formula with n = 8 and r = 2

$n C r = \frac{n!}{r!(n-r)!}\\\\8 C 2 = \frac{8!}{2!*(8-2)!}\\\\8 C 2 = \frac{8!}{2!*6!}\\\\8 C 2 = \frac{8*7*6!}{2!*6!}\\\\ 8 C 2 = \frac{8*7}{2!}\\\\ 8 C 2 = \frac{8*7}{2*1}\\\\ 8 C 2 = \frac{56}{2}\\\\ 8 C 2 = 28\\\\$