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3 years ago

Choose the correct simplification of the expression (−2x + 10y)(4x − 6y).

1 answer:

6 0

Well i have always gone by pemdas which is() exponits mulyiply or divide which ever comes first add subtract which ever comes first also

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A chemist has two alloys, one of which is 15% gold and 20% lead and the other which is 30% gold and 50% lead. How many grams of

vlabodo [156]

Answer: 490 grams of the first alloy should be used.

30 grams of the second alloy should be used.

Step-by-step explanation:

Let x represent the weight of the first alloy in grams that should be used.

Let y represent the weight of the second alloy in grams that should be used.

A chemist has two alloys, one of which is 15% gold and 20% lead. This means that the amount of gold and lead in the first alloy is

0.15x and 0.2x

The second alloy contains 30% gold and 50% lead. This means that the amount of gold and lead in the second alloy is

0.3y and 0.5y

If the alloy to be made contains 82.5 g of gold, it means that

0.15x + 0.3y = 82.5 - - - - - - - - - - - -1

The second alloy would also contain 113 g of lead. This means that

0.2x + 0.5y = 113 - - - - - - - - - - - - -2

Multiplying equation 1 by 0.2 and equation 2 by 0.15, it becomes

0.03x + 0.06y = 16.5

0.03x + 0.075y = 16.95

Subtracting, it becomes

- 0.015y = - 0.45

y = - 0.45/- 0.015

y = 30

Substituting y = 30 into equation 1, it becomes

0.15x + 0.3 × 30 = 82.5

0.15x + 9 = 82.5

0.15x = 82.5 - 9 = 73.5

x = 73.5/0.15

x = 490

6 0

3 years ago

Give A={a,b,c},how many subsets does A have including 0?

Tems11 [23]

Answer: 8 subsets

----------------------------------------------------------------------
----------------------------------------------------------------------

There are n = 3 elements in the given set, so there are 2^n = 2^3 = 2*2*2 = 8 subsets. Those 8 subsets are listed below

{a,b,c}
{a,b}, {a,c}, {b, c}
{a}, {b}, {c}
{ }

The first row is the original set. Any set is a subset of itself.
The second row represents subsets with exactly 2 elements.
The third row represents subsets with exactly 1 element
The fourth row is the empty set which can be written as $\varnothing$

8 0

3 years ago

Write an algebraic expression The quotient the of 72 divided by o =

Alchen [17]

72 ÷ o should be the algebraic expression.

4 0

4 years ago

Two boys searching for buried treasure are standing underneath the same tree. one boy walks 12 m east and then 12 m north. the o

mylen [45]

Let
The origin of coordinates the tree
r1 = vector position of the child 1.
r2 = vector position of the child 2
Child 1:
r1 = (12i + 12j)
Child 2:
r2 = (-18i + 11j)
The scalar product will be given by:
r1.r2 = ((12) * (- 18)) + ((12) * (11)) = - 84
The scalar product of their net displacements from the tree is -84m ^ 2

5 0

3 years ago

2x^2+3x+5=0 what are all the complex solutions? please i need help!!!

vesna_86 [32]

You'll want to use the quadratic formula:

-b (+/-) sqrt(b^2 - 4ac), all divided by 2a.

Under the square root you'll get:

-11

remember that the square root of -1 is i.

sqrt(-11) can be factored to sqrt(11*-1) and then sqrt(-1) * sqrt(11)

which becomes i*sqrt(11)

so your complex solution is:

-3 (+/-) (i*sqrt(11)), all over 4

4 0

3 years ago

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