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HACTEHA [7]
2 years ago
5

You went shopping for back to school and bought packs of pens and pencils. a pack of

Mathematics
1 answer:
Scrat [10]2 years ago
7 0

Answer:

5 packs of pens and 8 packs of pencils.

Step-by-step explanation:

Let the Pn and Pl stand for the number of packs of pens (Pn) and pencils (Pl) purchased.

We know that each pack of pens is $3 and each pack of pencils is $2.50.

We are also told that Pn + Pl = 13  [In total, 13 packs were purchased].

And we're told that $35 was spent.

The $35 must equal:  $3*Pn + $2.5*Pl  [the sum of the number of packs of each times the price per pack for each]

 3*Pn + 2.5*Pl = 35

Rearrange the first equation:

Pn + Pl = 13

Pn = 13 - Pl

Use this definition of Pn in the second equation:

3*Pn + 2.5*Pl = 35

3*(13 - Pl) + 2.5*Pl = 35

39 - 3Pl + 2.5Pl = 35

-0.5Pl = -4

Pl = 8

8 packs of pencils (Pl) were purchased.

This means the packs of pens purchased must be 5, since a total of 13 packs were purchased.

Check:

Does 5 packs of pens and 8 packs of pencils total $35?

5*($3) + 8*($2.5) = $35  ??

$15 + $20 = $35  ?

YES

You bought  5 packs of pens and 8 packs of pencils.

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What are the roots of this quadratic equation? 3x^2+10=4x
____ [38]

Step-by-step explanation:

The root of an equation is when x=0.

We need to rewrite this as 3x²-4x+10=0.

The quadratic formula is

(-b+or-sqrt(b²-4ac))/2a

so 4+or-sqrt(16-120)/2a

since the sqrt can no be negative this answer will have imaginary numbers.

(4+2i sqrt(26))6 and (4-2i sqrt(26))6

simplified is

x=(2+i sqrt(26))/3 and x=(2-i sqrt(26))/3

6 0
3 years ago
Find the x-coordinates where f '(x) = 0 for f(x) = 2x - sin(2x) in the interval [0, 2π].
Serggg [28]

Answer:

The x-coordinates where f '(x) = 0 for f(x) = 2x - sin(2x) in the interval [0, 2π] are: x=0, π, and 2π.


Step-by-step explanation:

f(x)=2x-sin(2x)

f'(x)=[f(x)]'

f'(x)=[2x-sin(2x)]'

f'(x)=(2x)'-[sin(2x)]'

f'(x)=2-cos(2x) (2x)'

f'(x)=2-cos(2x) (2)

f'(x)=2-2 cos(2x)


f'(x)=0, then:

2-2 cos(2x)=0

Solving for x. First solving for cos(2x): Subtracting 2 from both sides of the equation:

2-2 cos(2x)-2=0-2

-2 cos(2x)=-2

Dividing both sides of the equation by -2:

-2 cos(2x) / (-2)=-2 / (-2)

cos(2x)=1

If cos(2x)=1, then:

2x=2nπ

Dividing both sides of the equation by 2:

2x/2=2nπ/2

x=nπ


If n=-1→x=-1π→x=-π, and -π is not in the interval [0,2π], then x=-π is not in the solution.

If n=0→x=0π→x=0, and 0 is in the interval [0,2π], then x=0 is in the solution.

If n=1→x=1π→x=π, and π is in the interval [0,2π], then x=π is in the solution.

If n=2→x=2π, and 2π is in the interval [0,2π], then x=2π is in the solution.

If n=3→x=3π, and 3π is not in the interval [0,2π], then x=2π is not in the solution.


Solution: x=0, π, and 2π.

5 0
3 years ago
Which values are solutions to the inequality below? √x ≤ 5
Romashka [77]
\sqrt{x}  \leq 5

Find the real  region  for \sqrt{x}

\sqrt{x} is real for x \geq 0

= x  \geq 0

\sqrt{x}  \leq 5

Square both sides:

( \sqrt{x} )^2  \leq 5^2

5^2 = 5*5 =25

Refine:

x  \leq 25

Answer D

hope this helps!


5 0
3 years ago
Timothy is filling fish bowls with pebbles at his fish store. He wants to have $\frac{1}{6}$ of a pound of pebbles in each fish
Luba_88 [7]

Answer:

14

Step-by-step explanation:

Given that:

Each fish bowl to have pebbles of weight equivalent to = \frac{1}{6}

Total pounds of pebbles that Timothy can use = 2\frac{1}{3}

To find:

The greatest value of Total number of fish bowls that Timothy can fill ?

Solution:

First of all, we need to convert mixed fraction into a fractional number and then we also need to see division of two fractions.

Formula:

1. \ p\dfrac{q}{r} = \dfrac{p\times r+q}{r}\\2. \ \dfrac{\frac{a}{b}}{\frac{c}d}=\dfrac{a\times d}{b\times c}

Now, the given mixed fraction can be converted to fractional number as:

2\dfrac{1}{3} = \dfrac{2\times 3+1}{3} = \dfrac{7}{3}

Now, To find the total number of fish bowls that can be filled, we need to divide the total number of pounds with number of pounds of pebbles in each fish bowl.

So, the answer is:

\dfrac{\frac{7}{3}}{\frac{1}{6}}\\\Rightarrow \dfrac{7\times 6}{3\times 1}\\\Rightarrow \dfrac{42}{3}\\\Rightarrow \bold{14}

<em>14</em> number of fish bowls can be filled.

3 0
3 years ago
Plas help me with question 5
Arlecino [84]

Answer:

-1, 1, -1

Step-by-step explanation:

-1*-1*-1 = -1

1*-1 = -1

4 0
2 years ago
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