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3 years ago

D^2 + 2d - 8 = 0 explain plz

Mathematics

1 answer:

schepotkina [342]3 years ago

7 0

Answer:

d^2 +2d-8=0

first pick two numbers which add up to make +2 and by multiplying those two numbers they should be able to create -8.

so for example 4 and 2

4-2=2

4 x -2= -8

so now factorise:

d^2 +2d-8=0

d^2+4d-2d -8=0

d(d+4)-2(d+4)=0

d+4=0 d-2=0

d=-4 d=2

Step-by-step explanation:

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What is the approximate circumference of a semicircle with a radius of 12 centimeters?

lisabon 2012 [21]

You do Pi×Radius^2
so 24×Pi=75.4
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3 years ago

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Mikel asked her father how old he is gues the father said I you add the digits that make my age this year you'll get a number th

Alexxx [7]

Answer:

For the sum of the digits of Michelle’s father to drop to 1/3 of its’ former value, the second digit must go from 9 to 0, in one year.

Thus, if he is 39 this year, the sum of the digits of his age will be 12. Next year, when the sum of the digits would be 4+0, or 4, then the digits of his age would be 1/3rd of their former value.

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Step-by-step explanation:

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3 years ago

How do you write 5y-9=0 in standard form?

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Step-by-step explanation:

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3 years ago

You decide to put $2,000 in a savings account to save for a $3,000 downpayment on a new car. If the account has an interest rate

DanielleElmas [232]

It takes 10.155 years until you have $3,000 ⇒ 3rd

Step-by-step explanation:

The formula for compound interest, including principal sum is:

$A=P(1+\frac{r}{n})^{nt}$ , where

A is the future value of the investment/loan, including interest
P is the principal investment amount
r is the annual interest rate (decimal)
n is the number of times that interest is compounded per unit t
t is the time the money is invested or borrowed for

∵ You decide to put $2,000 in a savings account

∴ P = 2000

∵ You want to save for $3,000

∴ A = 3000

∵ The account has an interest rate of 4% per year and is

compounded monthly

∴ r = 4% = 4 ÷ 100 = 0.04

∴ n = 12 ⇒ compounded monthly

- Substitute all of these values in the formula above to find t

∵ $3000=2000(1+\frac{0.04}{12})^{12t}$

- Divide both sides by 2000

∴ $1.5=(1+\frac{1}{300})^{12t}$

∴ $1.5=(1\frac{1}{300})^{12t}$

- Change the mixed number to an improper fraction

∴ $(1.5)=(\frac{301}{300})^{12t}$

- Insert ㏒ for both sides

∴ $log(1.5)=log(\frac{301}{300})^{12t}$

- Remember $log(a)^{n}=nlog(a)$

∴ $log(1.5)=(12t)log(\frac{301}{300})$

- Divide both sides by $log(\frac{301}{300})$

∴ 121.84 = 12 t

- Divide both sides by 12

∴ 10.155 = t

It takes 10.155 years until you have $3,000

Learn more:

You can learn more about the compound interest in brainly.com/question/4361464

#LearnwithBrainly

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3 years ago

Find the altitude of a cylinder with with a radius of 9 and a surface area of approximately 791.68 units2.

Vika [28.1K]

In this question , it is given that we have a cylinder with with a radius of 9 and a surface area of approximately 791.68 units square.

The formula of surface area of cylinder is

$A= 2 \pi r^2 + 2 \pi r h$

Substituting the values of A and r, we will get

$791.68 = 2* \pi * 9^2 + 2 * \pi * 9*h
\\
791.68 = 162 \pi + 18 \pi h
\\
791.68 -162 \pi = 18 \pi h
\\
h = \frac{791.68 -162 \pi}{18 \pi}
\\
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So the height of the cylinder is 5 units .

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3 years ago