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2 years ago

Factorise the following 4(x-1)²-9 need solution

Mathematics

1 answer:

kumpel [21]2 years ago

6 0

Answer:x= 5/2 x= -1/2

Step-by-step explanation:

4(x-1)2-9

4(x2-2x+1) - 9

4x2 - 8x + 4 - 9

4x2 - 8x - 5

4x2 +2x - 10x - 5

2x(2x+1) - 5(2x+1)

(2x-5)(2x+1)

therefore, x= 5/2 x= -1/2

mark brainliest plzz

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What does the y intercept represent in distance vs time squared?

Evgen [1.6K]

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I hope this answers your question!

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2 years ago

The ideal (daytime) noise-level for hospitals is 45 decibels with a standard deviation of 10 db; which is to say, this may not b

WINSTONCH [101]

Answer:

(a) A 99% confidence interval for the actual mean noise level in hospitals is (44.02 db, 49.98 db).

(b) We can be 90% confident that the actual mean noise level in hospitals is 47 db with a margin of error of 1.89 db.

(c) Unless our sample (of 81 hospitals) is among the most unusual 2% of samples, the actual mean noise level in hospitals is between 44.41 db and 49.59 db.

Step-by-step explanation:

The problem is incomplete. The questions are:

(a) A 99% confidence interval for the actual mean noise level in hospitals is (44.02 db, 49.98 db).

For a 99% CI, the value of z is z=2.58

Then, the confidence interval for the mean is:

$M-z\sigma/\sqrt{n}\leq\mu\leq M-z\sigma/\sqrt{n}\\\\47-2.58*10/\sqrt{75} \leq\mu\leq47+2.58*10/\sqrt{75}\\\\47-2.98\leq\mu\leq47+2.98\\\\44.02\leq\mu\leq 49.98$

(b) We can be 90% confident that the actual mean noise level in hospitals is 47 db with a margin of error of 1.89 db.

For a 90% CI, the value of z is z=1.64.

Then, we can calculate the margin of error as:

$E=z*\sigma/\sqrt{n}=1.64*10/\sqrt{75}=1.89$

(c) Unless our sample (of 81 hospitals) is among the most unusual 2% of samples, the actual mean noise level in hospitals is between 44.41 db and 49.59 db.

The 2% tails data corresponds, in the standard normal distirbution, to the values of z whose absolute value is higher than 2.33.

The values of db for these critical values are:

$X_1=M+z_1*\sigma/\sqrt{n}=47+(-2.33)*10/\sqrt{81}=47-2.59=44.41\\\\\\ X_2=M+z_2*\sigma/\sqrt{n}=47+(2.33)*10/\sqrt{81}=47+2.59=49.59$

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3 years ago

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3 years ago

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2 years ago

Read 2 more answers

What is the length of a rectangle with width 20 in, and area 172 in2

timofeeve [1]

Answer:

8.6 inches (Rounded: 9 inches)

Step by Step:

1). w x l = A

2). 20 x l = 172

3). 172/20

4). 8.6

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2 years ago