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3 years ago

4x + 3y = 16

Mathematics

2 answers:

GalinKa [24]3 years ago

6 0

Answer:A

Step-by-step explanation:

ArbitrLikvidat [17]3 years ago

3 0

Answer:

Step-by-step explanation:

Given the 2 equations

4x + 3y = 16 → (1)

7x + 6y = 31 → (2)

Multiplying (1) by - 2 and adding to (2) eliminates the term in y

- 8x - 6y = - 32 → (3)

Add (2) and (3) term by term

- x = - 1 ( multiply both sides by - 1 )

x = 1

Substitute x = 1 into either (1) or (2)

Substituting in (1), then

(4 × 1) + 3y = 16

4 + 3y = 16 ( subtract 4 from both sides )

3y = 12 ( divide both sides by 3 )

y = 4

Solution is (1, 4 ) → A

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Find the sum or difference <br> 1/2 - 1/14<br> A.3/7<br> B.2/7<br> C.4/7

pogonyaev

Answer:

A.3/7

Step-by-step explanation:

1/2 - 1/14

We need to get a common denominator of 14

1/2 * 7/7 = 7/14

7/14 - 1/14 = 6/14

We can simplify by dividing the top and bottom by 2

3/7

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3 years ago

A friend has a 83% average before the final exam for a course. That score includes everything but the final, which counts for 25

Klio2033 [76]

Answer:

$\mathrm{Best\:course\:grade\:possible:\:}87.25\%,\\\mathrm{Minimum\:score\:on\:final\:to\:earn\:at\:least\:a\:75\%\:for\:the\:course:\:}51\%$

Step-by-step explanation:

Assuming the maximum score for the final is $100\%$ , we can multiply each score by its respective course weight and add them together to give a final score. If your friend did receive this maximum score of $100\%$ , their overall grade for the course would be:

$83(1-0.25)+100(0.25)=\fbox{$87.25\%$}$ .

To find the minimum score they need to earn a 75% for the course, we set up the following equation:

$83(1-0.25)+x(0.25)=75$ , where $x$ is the minimum score she needs.

Solving, we get:

$62.25+x(0.25)=75,\\x(0.25)=12.75,\\x=\fbox{$51\%$}$ .

8 0

2 years ago

A ball is thrown into the air by a baby alien on a planet in the system of Alpha Centauri with a velocity of 30 ft/s. Its height

Crank

Answer:

a) h = 0.1: $\bar v = -11\,\frac{ft}{s}$ , h = 0.01: $\bar v = -10.1\,\frac{ft}{s}$ , h = 0.001: $\bar v = -10\,\frac{ft}{s}$ , b) The instantaneous velocity of the ball when $t = 2\,s$ is $-10$ feet per second.

Step-by-step explanation:

a) We know that $y = 30\cdot t -10\cdot t^{2}$ describes the position of the ball, measured in feet, in time, measured in seconds, and the average velocity ( $\bar v$ ), measured in feet per second, can be done by means of the following definition:

$\bar v = \frac{y(2+h)-y(2)}{h}$

Where:

$y(2)$ - Position of the ball evaluated at $t = 2\,s$ , measured in feet.

$y(2+h)$ - Position of the ball evaluated at $t =(2+h)\,s$ , measured in feet.

$h$ - Change interval, measured in seconds.

Now, we obtained different average velocities by means of different change intervals:

$h = 0.1\,s$

$y(2) = 30\cdot (2) - 10\cdot (2)^{2}$

$y (2) = 20\,ft$

$y(2.1) = 30\cdot (2.1)-10\cdot (2.1)^{2}$

$y(2.1) = 18.9\,ft$

$\bar v = \frac{18.9\,ft-20\,ft}{0.1\,s}$

$\bar v = -11\,\frac{ft}{s}$

$h = 0.01\,s$

$y(2) = 30\cdot (2) - 10\cdot (2)^{2}$

$y (2) = 20\,ft$

$y(2.01) = 30\cdot (2.01)-10\cdot (2.01)^{2}$

$y(2.01) = 19.899\,ft$

$\bar v = \frac{19.899\,ft-20\,ft}{0.01\,s}$

$\bar v = -10.1\,\frac{ft}{s}$

$h = 0.001\,s$

$y(2) = 30\cdot (2) - 10\cdot (2)^{2}$

$y (2) = 20\,ft$

$y(2.001) = 30\cdot (2.001)-10\cdot (2.001)^{2}$

$y(2.001) = 19.99\,ft$

$\bar v = \frac{19.99\,ft-20\,ft}{0.001\,s}$

$\bar v = -10\,\frac{ft}{s}$

b) The instantaneous velocity when $t = 2\,s$ can be obtained by using the following limit:

$v(t) = \lim_{h \to 0} \frac{x(t+h)-x(t)}{h}$

$v(t) = \lim_{h \to 0} \frac{30\cdot (t+h)-10\cdot (t+h)^{2}-30\cdot t +10\cdot t^{2}}{h}$

$v(t) = \lim_{h \to 0} \frac{30\cdot t +30\cdot h -10\cdot (t^{2}+2\cdot t\cdot h +h^{2})-30\cdot t +10\cdot t^{2}}{h}$

$v(t) = \lim_{h \to 0} \frac{30\cdot t +30\cdot h-10\cdot t^{2}-20\cdot t \cdot h-10\cdot h^{2}-30\cdot t +10\cdot t^{2}}{h}$

$v(t) = \lim_{h \to 0} \frac{30\cdot h-20\cdot t\cdot h-10\cdot h^{2}}{h}$

$v(t) = \lim_{h \to 0} 30-20\cdot t-10\cdot h$

$v(t) = 30\cdot \lim_{h \to 0} 1 - 20\cdot t \cdot \lim_{h \to 0} 1 - 10\cdot \lim_{h \to 0} h$

$v(t) = 30-20\cdot t$

And we finally evaluate the instantaneous velocity at $t = 2\,s$ :

$v(2) = 30-20\cdot (2)$

$v(2) = -10\,\frac{ft}{s}$

The instantaneous velocity of the ball when $t = 2\,s$ is $-10$ feet per second.

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3 years ago

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Nostrana [21]

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