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mamaluj [8]
3 years ago
7

Using elimination, the equations 3x - 4y = 12 and x + 4y = 20 can be solved to show that x = 8 and y = 3. Is this true or false

?
Mathematics
2 answers:
OlgaM077 [116]3 years ago
8 0
3x - 4y = 12 ----- (1)
x + 4y = 20 ------ (2)

equation (2) x 3: 
3x + 12y = 60 ---(2a)

(2a) - (1):
12y - (-4y) = 60 - 12
12y +  4y = 48
16y = 48
y = 3 ---- sub into equation (2)

x + 4(3) = 20
x + 12 = 20
x = 8

Ans: x = 8 and y = 3 (True)


OLEGan [10]3 years ago
8 0
Both equations have a 4y term, so we can use elimination to easily solve the system.

3x - 4y = 12
x + 4y = 20
----------------
4x + 0y = 32

Now we can solve for x.

4x = 32

x = 8

Now we plug 8 in for x in either of the original equations to find y.

3(8) - 4y = 12

24 - 4y = 12

-4y = -12

y = 3

So yes, it is true that x = 8 and y = 3.

Hope this helps :)
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Number of people for whom registration fee is waived off = 50

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Part A: Money it will make from the grand opening memberships = ?

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⇒ Money it will make from the grand opening memberships = (Number of people who were charged registration fee ×  Registration fee per person) + (Number of people who registered × Monthly fee per person)

⇒ Money it will make from the grand opening memberships = (124 - 50) × 60 + (124 × 20)

⇒ Money it will make from the grand opening memberships = (74 × 60) + (124 × 20)

⇒ Money it will make from the grand opening memberships = (4,440) + (2,480)

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Part B: Money made in 6 months, from the original 124 people who joined at the grand opening = ?

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⇒ Money it will make from the grand opening memberships = (124 - 50) × 60 + (124 × 20 × 6)

⇒ Money it will make from the grand opening memberships = (74 × 60) + (124 × 20 × 6)

⇒ Money it will make from the grand opening memberships = 4,440 + 14,880

⇒ Money it will make from the grand opening memberships = $19,320

Hence, by the end of 6 months, the gym would have made $19,320

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