MATHEMATICS MIDDLE SCHOOL

Solve, using the substitution method 2x+4y=16 x-7=-4y

A. (0,-7)
B. (0,7/4)
C. (9,-1/2)
D. (17,-5/2)

PLEASE HELP ASAP !!

Answers

Answer 1
Answer: 2x+4y=16
x-7=-4y

4y=16-2x
4y=16-2(-4y+7)
4y=16+8y-14
-4y=2
-4y/-4=2/-4
y=-0,5

2x=16-4(-0,5)
2x=16+2
2x/2=18/2
x=9

C

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Answers

Don't get carried away with the exponent.

The exponent is not the number of years or the number of hours.
The exponent is the number of half-lifes.

In this one, the half-life is 12 hours, and they want to know
how much is left after 36 hours.  36 hours is 3 half-lifes.
The formula that you did is beautiful and almost perfect.
Just change that ugly exponent to the number of half-lifes (3)
and the answer will jump out at you.
half life formula is
F=P(1/2)^(t/h)

F=furure or ending amount
P=present amount
t=time elapsed
h=time the half life is


F=64(1/2)^(36/12)
F=64(1/2)^(3)
F=64(1/8)
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What is the answer to -12(k+4)=60

Answers

-12(k+4)=60\n\nk+4 = -5\n\n\boxed {k =-9}
-12 (K+4) = 60
Using Distributive Property:
-12K -48  =60
then 
-12 K = 60 + 48
-12K = 108
Divide both sides by  -12 

Then
K = -9

Convert 18/40 to a decimal

Answers

Answer:

45%

Step-by-step explanation:

18/40 = 9/20

1/20 = 5%

5 * 9 = 45

45%
The answer is 0.45 or 45% if you want a percentage

A trampoline gas an area of 49 • pi square feet. What is the diameter if the trampoline?

Answers

So,
if the area is 49pi, and the formula for the area of a circle is radius squared times pi,

The square root of 49 is 7.
The radius is 7.
To find the diameter, you multiply the radius by 2 because the radius is half of the diameter.
7x2=14
The diameter is 14 square feet.
Hope I helped!
area (S)= \pi r^2 
so
49 \pi= \pi r^2
so r^2=49 then r=7
diameter is 2*r=2*7=14 

Write each pair of fractions as a pair of fractions with a common denominator 3/4 and 7/8

Answers

3/4 

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4*2 = 8

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Please could someone help me with these questions sorry about the scribbling on one page I got stuck

Answers

question 4
So the polygon has 10 sides, to calculate how much all the interior angles are summed up, you have to see how many triangles you can fit into the polygon (this works for any polygon), in this case it is 8 (see file attached). Therefore you do 8 x 180 = 1440, so the overall angle is 1440º. Now you do 1440 : 10, because there are 10 equal angles, and that is 144º. 
Every angle has 144º

question 5
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