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garik1379 [7]
2 years ago
14

Solve the system using substitution x+5y=0 3y+2x=-21

Mathematics
2 answers:
Crazy boy [7]2 years ago
5 0

Answer:

\left \{ {{x = -15} \atop {y=3}} \right.

Step-by-step explanation:

\left \{ {{x + 5y = 0} (1) \atop {3y + 2x = -21}(2)} \right.  \left \{ {{x = -5y} \atop {3y + 2x = -21}} \right.    \left \{ {{x = -5y} \atop {3y + 2*(-5y) = -21}} \right.  \left \{ {{x = -5y} \atop {3y - 10y = -21}} \right. \\ \left \{ {{x = -5y } \atop {-7y = -21}} \right.  \left \{ {{x = -5y} \atop {y= 3 }} \right.  \left \{ {{x = -5 * 3} \atop {y=3}} \right.=> \left \{ {{x=-15} \atop {y=3}} \right.

pochemuha2 years ago
4 0
Ok done. Thank to me :>

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The sum of the digits of a certain two-digit number is 7. Reversing its digits increase the number by 9. What is the number?
Elis [28]
Let the two numbers be x and y.

According to your question;

x + y = 7
10y + x = 10x + y + 9

By equation 1 ; x = 7-y

Substituting the value of x ;

10y + ( 7 -y) = 10(7-y) + y + 9

9y + 7 = 70 -10y + y + 9

9y + 7 = 70 - 9y + 9

=> 18y = 70 -7 + 9
=> 18y = 72
=> y = 4

Substituting for x ;

x = 7 - y
=> x = 7 -4
=> x = 3

Thus, x = 3 and y = 4;
=> The number is 34.
5 0
3 years ago
Read 2 more answers
Solve the equation: 3 (x + 4) = 2x -- 8​
kotegsom [21]

Answer:

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Step-by-step explanation:

Let me know if you need the work.

5 0
3 years ago
Original Price Percent of Discount Sale Price<br> $ 5% $57
dalvyx [7]

Answer:

Discount:

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$54.15

Step-by-step explanation:

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Discount = 57 × 5/100

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You save = $2.85

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3 years ago
4. A rectangle has a diagonal of 8 cm. The diagonal creates a 60° angle at the base of the rectangle.
tamaranim1 [39]

9514 1404 393

Answer:

  a) see attachment

  b) base: 4, height: 4√3

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Step-by-step explanation:

a) The figure is drawn in the attachment

__

b) The side lengths of a 30-60-90 right triangle have the ratio ...

  1 : √3 : 2

Multiplying these by 4 gives the side lengths of each triangle created by the diagonal. The base (short leg) is 4 units; the height (long leg) is 4√3 units.

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c) The area is the product of base and height:

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7 0
3 years ago
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Aneli [31]
I cant directly give u the answer but here is some help:

for part a add up and solve the equazions on the whiteboard.

for part b subtract 90 from what you got from part a.


Hope this helps. Sorry i couldnt help more.
4 0
3 years ago
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