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Ronch [10]
3 years ago
6

Which equation is true?

Mathematics
2 answers:
ch4aika [34]3 years ago
6 0

Answer : 9x^2 - 25 = (3x - 5)(3x + 5)

(1) 9x^2 - 25 = (3x - 5)(3x - 5)

Use FOIL method to mulitply (3x – 5)(3x – 5)

(3x - 5)(3x - 5)  = 9x^2 - 30x + 25

(2) 9x^2 - 25 = (3x - 5)(3x + 5)

Use FOIL method to mulitply (3x - 5)(3x + 5)

(3x - 5)(3x - 5)  = 9x^2 - 15x + 15x - 25 = 9x^2 - 25

(3) 9x^2 - 25 = -(3x + 5)(3x + 5)

Use FOIL method to mulitply -(3x + 5)(3x + 5)

-(3x + 5)(3x + 5)  = -(9x^2 + 30x + 25) = -9x^2 -30x -25

(4) 9x^2 - 25 = -(3x + 5)(3x - 5)

Use FOIL method to mulitply -(3x + 5)(3x - 5)

-(3x + 5)(3x - 5)  = -(9x^2 - 25) = -9x^2 + 25

So equation 2 is true

padilas [110]3 years ago
4 0
Hello,

Answer B


But this is not an equation!!!!! (only an expression)
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a ship leave port p and sails on a bearing N50 degree E to Port Q 15km away.then it sails on a bearing of S45 degree E to Port R
Shtirlitz [24]

Answer:

Port r is 100° from Port p and 26km from Port p

Step-by-step explanation:

Lets note the dimension.

From p to q = 15 km = a

From q to r = 20 km= b

Angle at q = 50° + 45°

Angle at q = 95°

Ley the unknown distance be x

Distance from p to r is the unknown.

The formula to be applied is

X²= a²+ b² - 2abcosx

X²= 15² + 20² - 2(15)(20)cos95

X²= 225+400-(-52.29)

X²= 677.29

X= 26.02

X is approximately 26 km

To know it's direction from p

20/sin p = 26/sin 95

Sin p= 20/26 * sin 95

Sin p = 0.7663

P= 50°

So port r is (50+50)° from Port p

And 26 km far from p

3 0
4 years ago
Abigail was skateboarding home when the wheel axle of her skateboard broke. She had already traveled two thirds of the way home
OverLord2011 [107]

Answer:

I think that her taking the skateboard is 4 times as fast as her walking.

Step-by-step explanation:

I got this because she traveled twice as long and twice as fast on the skateboard, so if you multiply it together, there u have it.

4 0
4 years ago
If line a is perpendicular to line b and the slope of line a is 7 whats the slope of line b
amm1812

Answer:

If a line is perpendicular to another line, that means that the slope is completely opposite that of the original line.  The first thing that we do to the slope is we negate the number which means that if we have a slope of -7 our slope because 7 in this step.  In our case our slope is 7 so in this step it becomes -7.

Moving onto the second part which is to get the reciprocal of the number which means that if we have \frac{1}{2} then we would switch it to 2.  In our case our number is -7 so we would make that into a fraction like this -\frac{1}{7}.

In conclusion, our final slope of the perpendicular line is -\frac{1}{7}.

<u><em>Hope this helps!  Let me know if you have any questions</em></u>

8 0
2 years ago
Read 2 more answers
A small combination lock on a suitcase has 4 ​wheels, each labeled with the 10 digits 0 to 9. how many 4 digit combinations are
tamaranim1 [39]
This is the easiest way to solve this problem:

Imagine this represents how many combinations you can have for each of the 4 wheels (each blank spot for one wheel): __ __ __ __

For the first situation it says how many combos can we make if no digits are repeated.
We have 10 digits to use for the first wheel so put a 10 in the first slot 
10 __ __ __
Since no digit can be repeated we only have 9 options for the second slot
10 9_ __ __
Same for the third slot, so only 8 options
<u>10</u> <u> 9 </u> <u> 8 </u> __
4th can't be repeated so only 7 options left
<u>10</u> <u> 9 </u> <u> 8 </u> <u> 7 
</u><u>
</u>Multiply the four numbers together: 10*9*8*7 = 5040 combinations


For the next two do the same process as the one above.

If digits can be repeated? You have ten options for every wheel so it would look like this: <u>10</u> <u>10</u> <u>10</u> <u>10
</u>
10*10*10*10 = 10,000 combinations

If successive digits bust be different?
We have 10 for the first wheel, but second wheel only has 9 options because 2nd number can't be same as first. The third and fourth wheels also has 9 options for the same reason.

<u>10</u> <u> 9</u><u> </u> <u> 9 </u> <u> 9 </u>

10*9*9*9 = 7290 combinations






8 0
3 years ago
Solve<br> 2(x+4)= 20<br> Solve this please
Natasha2012 [34]
2x+8=20
2x=20-8
2x=12
12/2=x
6=x
6 0
3 years ago
Read 2 more answers
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