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3 years ago

Simplify the following expression -(-2a+7)

Mathematics

2 answers:

Marta_Voda [28]3 years ago

5 0

2a-7=0 A=7/2 is the correct answer

Pepsi [2]3 years ago

4 0

The answer would be 2a-7 because a negative times a negative is a postive so -(-2a) is 2a and negative times a postive is a negative so -(7) is -7

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If tanA+sinA=m and tanA-sinA=n.prove that m^2-n^2=4√mn

mash [69]

Let $a=\tan A$ and $b=\sin A$ . Then

$m^2-n^2=(a+b)^2-(a-b)^2=(a^2+2ab+b^2)-(a^2-2ab+b^2)=4ab$

$\implies m^2-n^2=4\tan A\sin A$

and

$mn=(a+b)(a-b)=a^2-b^2$

$\implies4\sqrt{mn}=4\sqrt{\tan^2A-\sin^2A}$

The expression under the square root can be rewritten as

$\tan^2A-\sin^2A=\dfrac{\sin^2A}{\cos^2A}-\sin^2A=\sin^2A\left(\dfrac1{\cos^2A}-1\right)=\sin^2A(\sec^2A-1)$

Recall that

$\sin^2A+\cos^2A=1\implies\tan^2A+1=\sec^2A$

so that

$\tan^2A-\sin^2A=\sin^2A\tan^2A$

and assuming $\sin A>0$ and $\tan A>0$ , we end up with

$4\sqrt{\tan^2A-\sin^2A}=4\tan A\sin A$

so that

$m^2-n^2=4\sqrt{mn}$

as required.

5 0

3 years ago

What is the slope of the line shown below

Radda [10]

Here's the slope form; (y2- y1) / (x2 - x1)

All you have to do now is just plug in the number into the formula.

(6 - -4) / (6 - 1) = 10/5

Then divide, and the answer is D. 2.

3 0

3 years ago

Read 2 more answers

2^x-1=128<br><br><br> show work pls! thank u :)

hichkok12 [17]

Hello from MrBillDoesMath!

Answer:

Take you pick below! (either x 8 or x = 7.01, approx, depending how the question is interpreted)

Discussion:

Interpretation 1

If the question is 2^(x -1) = 128, then as 2^7 = 128,

x-1 = 7 so x = 8

Interpretation 2

If the question is (2^x -1) = 128, then..

2^x = 128 + 1 = 129 =>

log(2^x) = log(129) =>

xlog(2) = log(129) =>

x = log (129) / log2 = 7.01

Regards,

MrB

4 0

3 years ago

Question 7 of 10<br> Choose two statements that are true for this expression.<br> 6r³ − 8x² - 40 +21

crimeas [40]

Based on the given parameters, bhe true statements are: the expression has four terms, and the term -40/y is a ratio.

<h3>How to determine the true statements?</h3>

The expression is given as:

6x^3 - 8x^2 - 40/y + 21

The above expression has four terms, and the terms are:

6x^3, - 8x^2,- 40/y and 21

Also, the term -40/y is a ratio

This is so because it is a quotient of two numbers

Hence, the true statements are: the expression has four terms, and the term -40/y is a ratio, based on the given parameters