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satela [25.4K]
2 years ago
7

Which of the following expressions is equivalent to 7y + 21 ?

Mathematics
1 answer:
Nikolay [14]2 years ago
8 0

Answer:

the answer is 7 ( y + 3) hope this helped

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A rectangular area of 36 f t2 is to be fenced off. Three sides will use fencing costing $1 per foot and the remaining side will
OLga [1]

Answer:

x = 8,49 ft

y  = 4,24  ft  

Step-by-step explanation:

Let  x be the longer side of rectangle   and  y  the shorter

Area of rectangle     =    36 ft²     36  =  x* y   ⇒ y =36/x

Perimeter of rectangle:

P  =  2x   +   2y    for convinience we will write it as    P  = ( 2x + y ) + y

C(x,y)   =  1 * ( 2x  +  y  )  +  3* y

The cost equation as function of x is:

C(x)  =  2x  + 36/x   + 108/x

C(x)  =  2x  + 144/x

Taking derivatives on both sides of the equation

C´(x)  = 2  - 144/x²

C´(x)  = 0         2  - 144/x² = 0       ⇒  2x²  -144 = 0    ⇒  x² =  72

x = 8,49 ft       y  = 36/8.49    y  = 4,24  ft    

How can we be sure that value will give us a minimun

We get second derivative

C´(x)  = 2  - 144/x²      ⇒C´´(x)  = 2x (144)/ x⁴

so C´´(x) > 0

condition for a minimum

7 0
3 years ago
Joy is training for a triathlon. She runs a distance of 2x miles, cycles a distance of (x2 + 7) miles, and swims a distance of (
Tpy6a [65]
Add

2x+x²+7+x-2=
x²+2x+x+7-2=
x²+3x+5=total distance
6 0
3 years ago
Read 2 more answers
Find the missing side of this right<br> triangle.<br> 19<br> X<br> X =<br> 16<br> ✓[?]
julia-pushkina [17]

Answer:

x = sqrt(105)

Step-by-step explanation:

Since this is a right triangle, we can use the Pythagorean theorem

a^2 + b^2 = c^2  where a and b are the legs and c is the hypotenuse

16^2 + x^2 = 19^2

256 + x^2 = 361

x^2 = 361 -256

x^2 =105

Take the square root of each side

sqrt(x^2) = sqrt(105)

x = sqrt(105)

8 0
2 years ago
If you start with 60% sunny days and after 200 days it decrease by 50%. How many days of the 200 were sunny days
qaws [65]
120 sunny days if there were 60% of em in 200 days
4 0
2 years ago
Please help me. I don't know what the answer is thank you!
nlexa [21]
Hello,

mes angle AEC=(69+105)/2=87
mes angle AED=(74+112)/2=93

Answer A
4 0
3 years ago
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