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1 year ago

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A classroom contains an equal number of boys and girls. if 10 girls leave, twice as many boys as girls remain. what was the orig

inal number of students present?

1 answer:

PolarNik [594]1 year ago

6 0

the answer of this question is 38 and i hope it s correct

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2x- 3y=9 5x+3y=12 How would i solve this? I dont understand this and i really need help with it!Also I have to graph the an

dedylja [7]

$\begin{cases} 2x- 3y=9 \\5x+3y=12 \end{cases}\\ + \ \ ------- \\ 7x=21 \ \ /: 7\\ \\x=\frac{21}{3}\\ \\ x=3 \\ \\2x- 3y=9$

$2*3-3y=9\\ \\6-3y =9\\ \\-3y=9-6\\ \\-3y=3 \ \ / :(-3)\\ \\x=-1\\ \\ \begin{cases} x=3\\y= -1 \end{cases}$

$graph\\ \\\begin{cases} 2x- 3y=9 \\5x+3y=12 \end{cases}\\ \\ \begin{cases} - 3y=-2x+9\ \ /:(-3) \\ 3y=-5x+12 \ \ /:3 \end{cases}\\ \\ \begin{cases} y= \frac{2}{3}x-3 \\ y=-\frac{5}{3}x+4 \end{cases}$

7 0

3 years ago

What is the volume of the cylinder?<br><br> Radius:3m<br><br> Height:17m

valentinak56 [21]

Answer:

480.66 m^3

Step-by-step explanation:

The formula for volume of a cylinder is πr^2h. when you input these values and solve for π you get π3^2(17) or approximately 480.66 m^3

Please mark as brainliest :)

5 0

3 years ago

Solve The Equation <br> 4x×9y=7<br> 4x-9y=9

hoa [83]

Answer:

$\large\boxed{x=\dfrac{9}{8}-\dfrac{\sqrt{109}}{8},\ y=-\dfrac{1}{2}-\dfrac{\sqrt{109}}{18}}\\or\\\boxed{x=\dfrac{9}{8}+\dfrac{\sqrt{109}}{2},\ y=-\dfrac{1}{2}+\dfrac{\sqrt{109}}{18}}$

Step-by-step explanation:

$\left\{\begin{array}{ccc}4x\times9y=7&(1)\\4x-9y=9&(2)\end{array}\right\\\\(2)\\4x-9y=9\qquad\text{subtract}\ 4x\ \text{from both sides}\\-9y=-4x+9\qquad\text{change the signs}\\9y=4x-9\qquad\text{substitute it to (1)}\\\\4x(4x-9)=7\qquad\text{use the distributive property}\ a(b+c)=ab+ac\\(4x)(4x)+(4x)(-9)=7\\(4x)^2-36x=7\\(4x)^2-2(4x)(4.5)=7\qquad\text{add}\ 4.5^2\ \text{to both sides}\\(4x)^2-2(4x)(4.5)+4.5^2=7+4.5^2\qquad\text{use}\ (a-b)^2=a^2-2ab+b^2$

$(4x-4.5)^2=7+20.25\\(4x-4.5)=27.25\to 4x-4.5=\pm\sqrt{27.25}\\\\4x-\dfrac{45}{10}=\pm\sqrt{\dfrac{2725}{100}}\\\\4x-\dfrac{45}{10}=\pm\dfrac{\sqrt{2725}}{\sqrt{100}}\\\\4x-\dfrac{45}{10}=\pm\dfrac{\sqrt{25\cdot109}}{10}\\\\4x-\dfrac{45}{10}=\pm\dfrac{\sqrt{25}\cdot\sqrt{109}}{10}\\\\4x-\dfrac{45}{10}=\pm\dfrac{5\sqrt{109}}{10}\qquad\text{add}\ \dfrac{45}{10}\ \text{to both sides}\\\\4x=\dfrac{45}{10}\pm\dfrac{5\sqrt{109}}{10}$

$4x=\dfrac{9}{2}\pm\dfrac{\sqrt{109}}{2}\qquad\text{divide both sides by 4}\\\\x=\dfrac{9}{8}\pm\dfrac{\sqrt{109}}{8}\\\\\text{Put the values of}\ x\ \text{to (2):}\\\\9y=4\left(\dfrac{9}{8}\pm\dfrac{\sqrt{109}}{8}\right)-9\\\\9y=\dfrac{9}{2}\pm\dfrac{\sqrt{109}}{2}-\dfrac{18}{2}\\\\9y=-\dfrac{9}{2}\pm\dfrac{\sqrt{109}}{2}\qquad\text{divide both sides by 9}\\\\y=-\dfrac{1}{2}\pm\dfrac{\sqrt{109}}{18}$

8 0

3 years ago

Enter your answer and show all the steps that you use to solve this problem.

slamgirl [31]

Answer:

h = -t+20

After 8 hours the candle will be 12 inches

Step-by-step explanation:

We have 2 points (time, inches)

(3,17) and (5,15)

We can find the slope

m = (y2-y1)/(x2-x1)

= (15-17)/(5-3)

= -2/2

= -1

We can use point slope form

y-y1 = m(x-x1)

Replace y with h and x with t

h-17 = -1 (t-3)

Distribute

h-17 = -t+3

Add 17 to each side

h-17+17 = -t+3+17

h = -t+20

3 0

3 years ago

An elevator descends into mine shaft at the rate of 6m/min. If the descend starts from 10m above the ground level , how long wil

AnnyKZ [126]

Answer: Hi!

So first, I'm going to convert "350 below ground level" to -350, as this is what "below ground level" represents.

Now, we should find the total distance traveled. Take the absolute value of -350 (350) and add it to 10, the metres above ground level. This is 360.

We already know the rate of travel; 6m/min. All we have to do now is divide the total distance (360) by the rate of travel (6)!

360 ÷ 6 = 60

So, it took 60 minutes, or one hour, for the elevator to travel down the shaft!

Hope this helps!

6 0

2 years ago