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3 years ago

Can someone help me with these questions and show work please and thank you

Mathematics

1 answer:

attashe74 [19]3 years ago

6 0

Answer:

11. 78

12. 4x² - 3x - 1

Step-by-step explanation:

11. Sum of n whole numbers = ½(n² + n)

Multiply

½*n² + ½*n

= n²/2 + n/2

To find the sum of the first 12 whole number, substitute 12 for n into the equation.

= 12²/2 + 12/2

= 144/2 + 12/2

= 72 + 6

= 78

12. Area of trapezoid = ½(a + b)*h

Where,

a = 5x - 4

b = 3x + 2

h = x + 1

Area = ½(5x - 4 + 3x + 2)*(x + 1)

Area = ½(8x - 2)*(x + 1)

Area = ½[8x(x + 1) -2(x + 1)]

= ½[8x² + 8x - 2x - 2]

Add like terms

= ½(8x² - 6x - 2)

= ½(8x²) - ½(6x) - ½(2)

= 4x² - 3x - 1

You might be interested in

The probability of getting less than 3 in a single throw of a dice is

BartSMP [9]

Answer:

There are two numbers {1,2} which is less than 3. so, required probability P(E) = 2/6 = 1/3.

Step-by-step explanation:

hope this helps

3 0

3 years ago

Set up a system of linear equations, and then solve for the indicated quantities.

hichkok12 [17]

9514 1404 393

Answer:

smaller: -4
larger: -1

Step-by-step explanation:

Substituting the given variables into the word problem, we have two equations:

3x +3y = -15

6x -3y = -21

Adding these equations eliminates y:

9x = -36

x = -4 . . . . divide by 9

Using this in the first equation, we have ...

3(-4) +3y = -15

-4 +y = -5 . . . . . divide by 3

y = -1 . . . . . . . . . add 4

The smaller number is -4; the larger is -1.

7 0

3 years ago

Using a graphing utility, find the exact solutions of the system. Round to the nearest hundredth and choose a solution to the sy

Margaret [11]

Answer:

Part 1) The exact solutions are

$(\frac{-1+\sqrt{21}} {2},4+\sqrt{21})$ and $(\frac{-1-\sqrt{21}} {2},4-\sqrt{21})$

Part 2) (1.79, 8.58)

Step-by-step explanation:

we have

$y=x^{2} +3x$ ----> equation A

$y=2x+5$ ----> equation B

we know that

When solving the system of equations by graphing, the solution of the system is the intersection points both graphs

Find the exact solutions of the system

equate equation A and equation B

$x^{2} +3x=2x+5\\x^{2} +3x-2x-5=0\\x^{2} +x-5=0$

The formula to solve a quadratic equation of the form

$ax^{2} +bx+c=0$

is equal to

$x=\frac{-b\pm\sqrt{b^{2}-4ac}} {2a}$

in this problem we have

$x^{2} +x-5=0$

$a=1\\b=1\\c=-5$

substitute in the formula

$x=\frac{-1\pm\sqrt{1^{2}-4(1)(-5)}} {2(1)}$

$x=\frac{-1\pm\sqrt{21}} {2}$

The solutions are

$x_1=\frac{-1+\sqrt{21}} {2}$

$x_2=\frac{-1-\sqrt{21}} {2}$

Find the values of y

First solution

For $x_1=\frac{-1+\sqrt{21}} {2}$

$y=2(\frac{-1+\sqrt{21}} {2})+5$

$y=-1+\sqrt{21}+5\\\\y=4+\sqrt{21}$

The first solution is the point $(\frac{-1+\sqrt{21}} {2},4+\sqrt{21})$

Second solution

For $x_2=\frac{-1-\sqrt{21}} {2}$

$y=2(\frac{-1-\sqrt{21}} {2})+5$

$y=-1-\sqrt{21}+5\\\\y=4-\sqrt{21}$

The second solution is the point $(\frac{-1-\sqrt{21}} {2},4-\sqrt{21})$

Round to the nearest hundredth

First solution

$(\frac{-1+\sqrt{21}} {2},4+\sqrt{21})$ -----> $(1.79,8.58)$

$(\frac{-1-\sqrt{21}} {2},4-\sqrt{21})$ -----> $(-2.79,-0.58)$

see the attached figure to better understand the problem

6 0

3 years ago

As the teams fundraiser,Agnes and Betty both sold candy bars at the end of the fundraiser Agnes determined that she sold 8 more

Romashka-Z-Leto [24]

Answer:

356

Step-by-step explanation:

5 0

2 years ago

What is the sum of 3/7, 4/5, and 2/3 rounded to two decimal places

bagirrra123 [75]

Hello!!

Total = 3/7 + 4/5 + 2/3

= 0.428571429 + 0.8 + 0.66666667

= 199/105

= 1.89524.....

≈ 1.90 (rounded to two decimal places)

Good luck :)

3 0

3 years ago