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4 years ago

Help me please i dont understand!!

Mathematics

1 answer:

MAVERICK [17]4 years ago

7 0

$15.\\(x+7)-(3x+2)=x+7-3x-2=(x-3x)+(7-2)=-2x+5\\\\16.\\(3t+5)-(4t-7)=3t+5-4t+7=(3t-4t)+(5+7)=-t+12\\\\17.\\(3r-5)-(r^2-2r+6)=3r-5-r^2+2r-6=(-r^2)+(3r+2r)+(-5-6)=-r^2+5r-11\\\\18.\\(u^2-6u+7)-(u^2+6u-8)=u^2-6u+7-u^2-6u+8\\\\=(u^2-u^2)+(-6u-6u)+(7+8)=-12u+15$

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How do I do expanded form

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3 years ago

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What is the value of cos(15degrees)?

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Answer:

The answer is root 6 + root 2/4

Step-by-step explanation:

Cos (15)

Rewrite the expression

write (15 degrees) as a difference

cos ( 45 degrees - 30 degrees)

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Use cos ( t - s ) = cos (t) cos (s) + sin (t) sin (s)

to expand the expression

cos (45 degrees) cos ( 30 degrees) + sin ( 45 degrees ) sin ( 30 degrees)

calculate the expression

use the trigonometric values table or unit circle to calculate the expression

root 2/root 2 × cos (30 degrees) + sin (45 degrees) sin (30 degrees)

root 2/root 2 × root 3/root 2 + sin (45 degrees) sin (30 degrees)

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root 2/root2 × root 3/root 2 + root 2/root 2 × 1/2

Multiply

root 2/root 2 × root 3/root 2 only

Multiply by the fractions

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Multiply root 2/ root 2 × 1/2 only

6 root / root 4 + root 2/ root 4

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3 years ago

In a given course a student receives preliminary examination grades of 81, 85, and 95. The final examination is weighed for one-

Vsevolod [243]

Answer:

B. 96

Step-by-step explanation:

Let x represent score of final third exam.

We have been given that in a given course a student receives preliminary examination grades of 81, 85, and 95.

Let us find average of preliminary scores.

$\frac{81+85+95}{3}=\frac{261}{3}=87$

We have been given that the final examination is weighed for one-third and the average of the preliminary grades is weighed as 2/3 of the final grade. This means that final grade is equally weighed into 3 parts. The two parts are 87 each and third part is x.

Using our given information, we can set an equation as:

$\frac{87+87+x}{3}=90$