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3 years ago

(8m-3n)^2 - (4m+3n)^2

Mathematics

1 answer:

natulia [17]3 years ago

4 0

Answer:

$48m^2-72mn$

Step-by-step explanation:

We need to solve $(8m-3n)^2 - (4m+3n)^2$

We know that,

$(a+b)^2=a^2+b^2+2ab\\\\(a-b)^2=a^2+b^2-2ab$

Using the above formula,

$(8m-3n)^2 - (4m+3n)^2=(8m)^2+(3n)^2-2(8m)(3n)-[(4m)^2+(3n)^2+2(4m)(3n)]\\\\=64m^2+9n^2-48mn-(16m^2+9n^2+24mn)\\\\=64m^2+9n^2-48mn-16m^2-9n^2-24mn\\\\=48m^2-48mn-24mn\\\\=48m^2-72mn$

So, the final answer is $48m^2-72mn$ .

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PLEASE HELP!! URGENT

tatiyna

Answer:

y=105

Step-by-step explanation:

82+75+x=180

157+x=180

x=23

82+23=y

105=y

4 0

3 years ago

The total amount of money earned by all three plumbers on Monday was $1,400. On Tuesday they earned a total of $1,660, and on We

Alekssandra [29.7K]

Set of equations that can be used to calculate rate for each plumber:
2A+8B+8C = 1,400 --- (1)
4A+7B+10C = 1,660 --- (2)
3A+9B+9C = 1,660 --- (3)
------------------------------------
2*(1) - (2)
------------------------------------
4A+16B+16C = 2,800
4A+7B+10C = 1,660 -
------------------------------------
9B+6C = 1,140 --- (4)
------------------------------------
3(2) -4(3)
-----------------------------------
12A+21B+30C = 4,980
12A+36B+36C = 6,600 -
-----------------------------------
-15B-6C = -1,620 --- (5)
------------------------------------
(4) + (5)
------------------------------------
9B+6C = 1140
-15B-6C = -1620 +
-------------------------------------
-6B = -480 => 6B = 480 => B = 480/6 = 80
-------------------------------------------------------
Using (4), 9(80)+6C = 1140
720+6C = 1140 => 6C = 1140-720 = 420 => C = 420/6 = 70
------------------------------------------------------------------------------
Using (1), 2A+8(80)+8(70) = 1400
2A+640+560 =1400 => 2A = 1400-640-560 = 200 => A = 200/2 = 100
----------------------------------------------------------------------------------------------
The rates are:
A = $100
B = $80
C = $70
--------------------------------
On Thursday, number of calls: A = 4 hrs, B = 6 hrs, C = 3 hrs
Money earned = 4*100+6*80+3*70 = $1,090

6 0

3 years ago

Read 2 more answers

A cylinder shaped can needs to be constructed to hold 400 cubic centimeters of soup. The material for the sides of the can costs

LenKa [72]

Answer:

The dimensions of the can that will minimize the cost are a Radius of 3.17cm and a Height of 12.67cm.

Step-by-step explanation:

Volume of the Cylinder=400 cm³

Volume of a Cylinder=πr²h

Therefore: πr²h=400

$h=\frac{400}{\pi r^2}$

Total Surface Area of a Cylinder=2πr²+2πrh

Cost of the materials for the Top and Bottom=0.06 cents per square centimeter

Cost of the materials for the sides=0.03 cents per square centimeter

Cost of the Cylinder=0.06(2πr²)+0.03(2πrh)

C=0.12πr²+0.06πrh

Recall: $h=\frac{400}{\pi r^2}$

Therefore:

$C(r)=0.12\pi r^2+0.06 \pi r(\frac{400}{\pi r^2})$

$C(r)=0.12\pi r^2+\frac{24}{r}$

$C(r)=\frac{0.12\pi r^3+24}{r}$

The minimum cost occurs when the derivative of the Cost =0.

$C^{'}(r)=\frac{6\pi r^3-600}{25r^2}$

$6\pi r^3-600=0$

$6\pi r^3=600$

$\pi r^3=100$

$r^3=\frac{100}{\pi}$

$r^3=31.83$

r=3.17 cm

Recall that:

$h=\frac{400}{\pi r^2}$

$h=\frac{400}{\pi *3.17^2}$

h=12.67cm

The dimensions of the can that will minimize the cost are a Radius of 3.17cm and a Height of 12.67cm.

3 0

3 years ago

Almost all companies utilize some type of year-end performance review for their employees. Human Resource (HR) at a university's

balu736 [363]

Answer:

The Answer is 76.

Step-by-step explanation:

Given the normal distribution " 10% of employees (rated) exemplary, 20% distinguished, 40% competent, 20% marginal, and 10% unacceptable'', we can see that exemplary employees are top 10% rated employees.

We have the formula for normal distribution:

z=(X-M)÷σ

where z is the minimum z-score for top 10% employee, X is the minimum score for top 10% employee, M is the mean of the score distribution, σ is the standard deviation of the score distribution.

The z-score we are looking for is the value "a" that separates the highest 10% from the lowest 90% i.e. P(z≤a)=0.90

If we look at z-table, corresponding value for a is 1.28155

We can now put the values in the formula:

1.28155= $\frac{X-50}{20}$

So X=(1.28155×20)+50=75.631

Therefore minimum score for exemplary employee is 76.

3 0

3 years ago

Number of stickers is less than 1145 but greater than 1100. How many stickers?

dimaraw [331]

45 stickers because 1145 - 1100 = 45.

5 0

3 years ago

(8m-3n)^2 - (4m+3n)^2​

(8m-3n)^2 - (4m+3n)^2