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mojhsa [17]
3 years ago
6

Solve the quadratic equation by square roots: 1. 4x²= 81 2. (4x-3)²+7=39

Mathematics
1 answer:
Nataly [62]3 years ago
7 0

Answer:

see explanation

Step-by-step explanation:

(1)

given

4x² = 81 ( divide both sides by 4 )

x² = \frac{81}{4} ( take the square root of both sides )

x = ± \sqrt{\frac{81}{4} } = ± \frac{9}{2}

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

(2)

subtract 7 from both sides

(4x - 3)² = 32 ( take the square root of both sides )

4x - 3 = ± \sqrt{32} = ± 4\sqrt{2}

Add 3 to both sides

4x = 3 ± 4\sqrt{2} ( divide both sides by 4 )

x = \frac{3}{4} ± \sqrt{2}

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Four percent of Jennie's skin cells were burned when she escaped from a fire. If 3.7 x 10^10 of her skin cells were burned then,
baherus [9]

Answer:

355.2

Step-by-step explanation:

Given:

Four percent of Jennie's skin cells were burned

Total skin cells having Jennie = 3.7 x 10^10

                                                  = 3.7\times10\times10 = 370

To find:

How man skin cells were not burned ?

Solution:

Total skin cells having Jennie = 370

Percent of Jennie's skin cells were burned = 4%

Skin cells burned  from a fire = 370 \ of 4\%

                                                = 370\times\frac{4}{100} =\frac{1480}{100}

                                                = 14.8

Remaining skin cells which not burned = 370 - 14.8 = 355.2

Therefore,  355.2 skin cells were not burned.

8 0
3 years ago
I need help with the first
Sphinxa [80]

Answer:

eq: s= 5w + 3

Step-by-step explanation:

independent: number of weeks

dependent:  amount of stickers

the amount of stickers depend on how many weeks pass by :) (English is my second language so I may write weird)

8 0
2 years ago
If 3 times an integer is 12 more than the next consecutive odd<br> integer, what is that integer?
Ilia_Sergeevich [38]

Answer:

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Step-by-step explanation:

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7 0
2 years ago
There are more swimmers under 30 years old than there are age 50 and above.
garik1379 [7]

Answer:

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Step-by-step explanation:

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7 0
2 years ago
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A man invests his savings in two accounts, one paying 6% and the other paying 10% simple interest per year. He puts twice as muc
Masteriza [31]

Let x represent amount invested in the higher-yielding account.

We have been given that a man puts twice as much in the lower-yielding account because it is less risky. So amount invested in the lower-yielding account would be 2x.

We are also told that his annual interest is $6600 dollars. We know that annual interest for one year will be principal amount times interest rate.

I=Prt, where,

I = Amount of interest,

P = Principal amount,

r = Annual interest rate in decimal form,

t = Time in years.

We are told that interest rates are 6% and 10%.

6\%=\frac{6}{100}=0.06

10\%=\frac{10}{100}=0.10

Amount of interest earned from lower-yielding account: 2x(0.06)=0.12x.

Amount of interest earned from higher-yielding account: x(0.10)=0.10x.

0.12x+0.10x=6600

Let us solve for x.

0.22x=6600

\frac{0.22x}{0.22}=\frac{6600}{0.22}

x=30,000

Therefore, the man invested $30,000 at 10%.

Amount invested in the lower-yielding account would be 2x\Rightarrow 2(30,000)=60,000.

Therefore, the man invested $60,000 at 6%.

8 0
3 years ago
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