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3 years ago

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Mathematics

2 answers:

8_murik_8 [283]3 years ago

8 0

Answer:

i think its D but im not exactly sure

LenaWriter [7]3 years ago

7 0

Answer:

Step-by-step explanation:

Subtract 60 from 80 to get 20, and divide 20 by 80 to get 1/4, which can be converted to 25%.

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Write as a decimal of a) 35Km5m to Km b) 1457ml to L<br><br>Please Help

podryga [215]

The line in a fraction that separates the numerator and denominator can be rewritten using the division symbol. So, to convert a fraction to a decimal, divide the numerator by the denominator. If required, you can use a calculator to do this. This will give us our answer as a decimal.

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3 years ago

The ratio 2/5 to 1/3 has a unit rate if 2/15

Bas_tet [7]

Answer:

Step-by-step explanation:

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3 years ago

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PSYCHO15rus [73]

Take some trinomial expansions to find some useful expressions and their values.

• 2nd degree expansion

$x + y + z = 7 \\\\ \implies (x+y+z)^2 = x^2+y^2+z^2+2(xy+xz+yz) = 7^2 \\\\ \implies xy+xz+yz = \dfrac{49-33}2 = 8$

• 3rd degree expansion

$x+y+z=7 \implies (x+y+z)^3 = 7^3 \\\\ \implies \\ 243 = x^3+y^3+z^3+3(x^2y+x^2z+xy^2+y^2z+xz^2+yz^2) + 6xyz \\\\ \implies \\ x^2y+x^2z+xy^2+y^2z+xz^2+yz^2 + 2xyz = \dfrac{343 - 145}3 = 66$

• 4th degree expansion

$x+y+z=7 \implies (x+y+z)^4 = 7^4 \\\\ \implies \\ 2401 = x^4+y^4+z^4+4(x^3y+x^3z+xy^3+y^3z+xz^3+yz^3) \\\\ ~~~~~~~~~~~~+ 6(x^2y^2+x^2z^2+y^2z^2) + 12(x^2yz+xy^2z+xyz^2) \\\\ \implies \\\\ x^4+y^4+z^4 = 2401 - 4(x^3y+x^3z+xy^3+y^3z+xz^3+yz^3) \\\\ ~~~~~~~~~~~~~~~~~~~~~~- 6(x^2y^2+x^2z^2+y^2z^2) - 12(x^2yz+xy^2z+xyz^2)$

Simplify:

$x^3y+x^3z+xy^3+y^3z+xz^3+yz^3 \\\\ ~~~~ = x^2 (xy+xz) + y^2 (xy+yz) + z^2 (xz + yz) \\\\ ~~~~ = x^2 (xy+xz+yz) + y^2 (xy+xz+yz) + z^2 (xy + xz + yz) - (x^2yz + xy^2z + xyz^2) \\\\ ~~~~ = (x^2+y^2+z^2) (xy+xz+yz) - xyz (x+y+z) \\\\ ~~~~ = 264 - 7xyz$

$x^2y^2+x^2z^2+y^2z^2 \\\\ ~~~~ = xy\cdot xy + xz \cdot xz + yz \cdot yz \\\\ ~~~~ = xy(xy+xz+yz) + xz(xy+xz+yz) + yz(xy+xz+yz) - 2(x^2yz+xy^2z+xyz^2) \\\\ ~~~~ = (xy+xz+yz)^2 - 2xyz(x+y+z) \\\\ ~~~~ = 64 - 14xyz$

$x^2yz+xy^2z+xyz^2 = xyz (x + y + z) = 7xyz$

Then the equation we got from the 4th degree expansion reduces to

$x^4+y^4+z^4 = 2401 - 4(264-7xyz) - 6(64-14xyz) - 12(7xyz) \\\\ ~~~~~~~~~~~~~~~~~= 961 + 28xyz$

and all we need now is the value of $xyz$ .

In the 3rd degree expansion, we have

$x^2y+x^2z+xy^2+y^2z+xz^2+yz^2 \\\\ ~~~~ = x(xy + xz) + y(xy + yz) + z(xz + yz) \\\\ ~~~~ = x(xy+xz+yz) + y(xy+xz+yz) + z(xy+xz+yz) - 3xyz \\\\ ~~~~ = (x+y+z)(xy+xz+yz) - 3xyz \\\\ ~~~~ = 56 - 3xyz \\\\ \implies (56 - 3xyz) + 2xyz = 66 \\\\ \implies xyz = -10$

So, we end up with

$x^4+y^4+z^4 = 961 - 280 = \boxed{681}$

4 0

1 year ago

Please help! I’ll give you brainlyest answer!

Mrrafil [7]

Answer:

The answer to your question is the first choicd

3 0

3 years ago

How do I find the perimeter of a triangle with sides 3ft 8in., 2ft 10in., and 4 ft?

Dmitriy789 [7]

Formula for triangle perimeter is: a + b + c. In this scenario we have:

a = 3 feet 8 inches
b = 2 feet 10 inches
c = 4 feet

a + b + c =
= 3 ft + 8 in + 2 ft + 10 in + 4 ft =
= 9 ft + 18 in

We know that 1 foot is 12 inches, so we can simplify the result to this form:

10 ft + 6 in

or:

<u>10.5 feet</u>

4 0

3 years ago