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3 years ago

23. * MULTIPLE CHOICE Which is the correct factorization of -45x^2 + 20y^2

Mathematics

1 answer:

skad [1K]3 years ago

7 0

Answer:

c)-5(3x+2y)(3x-2y)

Step-by-step explanation:

1) lets find out if -45 and 20 have a GCF

-45 and 20 are both dividable by -5 so

-5(9x^2-4y^2)

1) you can see that 9 and -4 are perfect square so:

-5(3x+2y)(3x-2y)

Recheck:

1) lets use FOIL to see if this is right(if its right we will get back our original equation)

-5(9x^2-6xy+6xy-4y^2)

-5(9x^2-4y^2)

-45x^2+20y^2

hope this helps!

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2 years ago

The endpoints of cd are c(7,9) and d(4,-3) find the coordinates of the midpoint m

harkovskaia [24]

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4 years ago

A boat traveled 153 miles downstream and back. The trip downstream took 9 hours. The trip back took 17 hours. What is the speed

fgiga [73]

Speed of boat in still water is 13 miles per hour and speed of current is 4 miles per hour

<h3>Solution:</h3>

Let s = the speed of the boat in still water in miles/hour

Let c = the speed of the current in miles/hour

Formula to remember:

If the speed of a boat in still water is s miles/hr and the speed of the current is c miles/hr, then:

Speed downstream = (s + c) miles per hour

Speed upstream = (s - c) miles per hour

Given:

boat traveled 153 miles downstream and back

distance for downstream = 153 miles

distance for upstream = 153 miles

time taken for downstream = 9 hours

Time taken for upstream = 17 hours

The relation between speed, distance and time is given as:

$distance = speed \times time$

For downstream:

$153 = (s + c) \times 9$

$s + c = \frac{153}{9} = 17$

s + c = 17 ------- eqn 1

For upstream:

$153 = (s - c) \times 17\\\\s - c = \frac{153}{17} = 9$

s - c = 9 ------- eqn 2

Let us solve eqn 1 and eqn 2 to find values of "s" and "c"

Add eqn 1 and eqn 2

s + c = 17

s - c = 9

(+) -------------

2s = 26

Substitute s = 13 in eqn 1

13 + c = 17

c = 17 - 13 = 4

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3 years ago

If the Pacific plate moves around 5cm a year how long will it take Los Angeles to move one kilometer?

mr_godi [17]

We need to work with the same units, so first, we convert 1 km to cm.

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Now we divide 100,000 cm by 5 cm.

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3 years ago

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Hope this helps with your question;)

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