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user100 [1]
3 years ago
7

Solve 3x+2y=7 and x-4y=-21 by using substitution

Mathematics
2 answers:
gtnhenbr [62]3 years ago
7 0
\left \{ {{3x+2y=7\ \ | *2} \atop {x-4y=-21}} \right. \\\\ \left \{ {{6x+4y=14} \atop {x-4y=-21}} \right.\\\\+----\\Addition\\\\
7x=14-21\\
7x= -7\ \ \ | divide\ by\ 7\\\\
x=-1\\
2y=7-3x\\
y=\frac{7-3x}{2}=\frac{7+3}{2}=5\\\\Solution\ \\ \left \{ {{y=5} \atop {x=-1}} \right.
Aliun [14]3 years ago
6 0
3x + 2y = 7
x - 4y = - 21

6x + 4y = 14
x - 4y = - 21

6x + x = 14 - 21
7x = - 7
x = - 7 /7
x = - 1

y = (7 - 3x)/2 
y = (7 - 3 x (- 1))/2
y = (7 - (- 3))/2
y = (7 + 3)/2
y = 10/2
y = 5

Ans : x = - 1
        y = 5
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notka56 [123]

Answer:

Answer is A

Step-by-step explanation:

(14x^4y^6)/(7x^8y^2)

because everything is one term, you can split into three terms

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multiplying these three terms will get us the starting term

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with division of exponents, you subtract the smaller exponent (4), from the big exponent (8), and leave it on the same side (bottom) as the big exponent

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same thing with our y's

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this time, the term stays on the top

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take the simplified terms and multiply them together

(2) * (1/x^4) * (y^4) =

A: (2y^4) / (x^4)

7 0
3 years ago
A rabbit travels 3/4 miles in 7/8 of an hour. whats the rabbits unit rate?
Mnenie [13.5K]

Answer:

= 0.857143 miles per hour

Step-by-step explanation:

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5 0
3 years ago
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RoseWind [281]
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Steps:

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4 0
3 years ago
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we know that

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the y-coordinate of the fourth point is the same y coordinate of (-4,4)

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8 0
2 years ago
Can anyone explain how to expand and simplify 3(2a+5) +5 (a-2)
Step2247 [10]
Take the first bracket and it's multiplication, 3(2a+5)
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