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salantis [7]
2 years ago
7

Solve the following simultaneous equations 2x+5y=0 and 3x-4y=23

Mathematics
1 answer:
Elodia [21]2 years ago
7 0

Answer:

x = 5, y = -2

Step-by-step explanation:

2x + 5y = 0 --- Equation 1

Equation 1×3: <u>6x</u> + 15y = 0 --- Equation 2

3x - 4y = 23 --- Equation 3

Equation 3×2: <u>6x</u> - 8y = 46 --- Equation 3

<em>We will be eliminating 6x from Equation 2. </em>

Equation 3-2: 6x - 8y - 6x - 15y = 46-0

-23y = 46

y = 46 ÷ -23

<u>y = -2 </u>

Substitute y = -2 into Equation 1:

2x + 5y = 0

2x + 5(-2) = 0

2x + (-10) = 0

2x - 10 = 0

2x = 10

x = 10 ÷ 2

<u>x = 5 </u>

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Peter leaves Mitchell's house traveling 30 mph. Mitchell leaves 15 min later, trying to catch up to peter, going 40 mph. if they
UkoKoshka [18]

Answer:

  45 minutes

Step-by-step explanation:

At 30 mph for 1/4 hour, Peter has a 7.5 mile head start. After he leaves, Mitchell closes that gap at the rate of 40-30 = 10 miles per hour. It will take him ...

  t = d/s

  t = (7.5 mi)/(10 mi/h) = 0.75 h

to catch Peter.

Mitchell will catch Peter in 45 minutes.

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<em>Alternate Solution</em>

Another way to look at it is that Mitchell's 10 mph advantage is 1/3 of Peter's speed, so it will take 1/(1/3) = 3 times the period of Peter's head start:

  3 × 15 minutes = 45 minutes . . . for Mitchell to catch Peter

_____

You can write equations involving time and distance and see where the distances traveled become the same. You need to be careful choosing the time reference, since you're concerned with Mitchell's travel time. I personally prefer to work "head start" problems by considering the differences in time and speed, as above. This is where you end up using the equations approach, anyway.

4 0
3 years ago
Please help me, please
LiRa [457]
Answer: D: -2
explanation:
1. divide fractions inside brackets by multiplying by the reciprocal
1/4 • 4/7
= 4/28
2. multiply 4/28 by 7/5
= 28/140 which can be reduced to 1/5
3. multiply by -10
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8 0
2 years ago
Read 2 more answers
What is an integer between the square root of 30 and 4*Pi divided by 3
Andru [333]
\sqrt{30}\approx5.5\\&#10;\frac{4\pi}{3}\approx4.2

It's 5.
3 0
3 years ago
What are the values of X and Z.
stiv31 [10]

Answer:

x = 12, z  = 86

Step-by-step explanation:

Two angles are called supplementary when their measures add up to 180 degrees.

(12x -58  + 13x - 62 ) = 180°

12 x + 13x -58 - 62 = 180°

25x - 120 = 180

25x = 180 + 120

x = 300/ 25

x = 12

----------------------------------------------------------------------------------

(z° + 13x - 62) = 180

(z° + 13(12) - 62 )= 180

(z° +  156 - 62 )= 180

(z° + 94 ) = 180

z° = 180 - 94

z  = 86

5 0
3 years ago
For every 2 hours that Robert spends studying for a math test he spends 3 hours working on English. If he spends 21 hours one mo
nataly862011 [7]

Answer:

31.5 hours studying English

Step-by-step explanation:

2 math hours  = 3 english hours

21 math hours = ? english hours

21/2 = 10.5

10.5 * 3 = 31.5

5 0
3 years ago
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