How do you write 7.75 in scientific notation?<br><br><br><br> i neeeed helps asap!

I need help on this problem, if you can help me ill really be grateful. If you could also explain it that would be great.

givi [52]

Answer:

x=3

Step-by-step explanation:

The square root of 225 is 15

so 15=4x+3

-3 -3

12=4x

If 12=4x then x=3

5 0

2 years ago

The spherical balloon is inflated at the rate of 10 m³/sec. Find the rate at which the surface area is increasing when the radiu

rjkz [21]

The balloon has a volume $V$ dependent on its radius $r$ :

$V(r)=\dfrac43\pi r^3$

Differentiating with respect to time $t$ gives

$\dfrac{\mathrm dV}{\mathrm dt}=4\pi r^2\dfrac{\mathrm dr}{\mathrm dt}$

If the volume is increasing at a rate of 10 cubic m/s, then at the moment the radius is 3 m, it is increasing at a rate of

$10\dfrac{\mathrm m^3}{\mathrm s}=4\pi (3\,\mathrm m)^2\dfrac{\mathrm dr}{\mathrm dt}\implies\dfrac{\mathrm dr}{\mathrm dt}=\dfrac5{18\pi}\dfrac{\rm m}{\rm s}$

The surface area of the balloon is

$S(r)=4\pi r^2$

and differentiating gives

$\dfrac{\mathrm dS}{\mathrm dt}=8\pi r\dfrac{\mathrm dr}{\mathrm dt}$

so that at the moment the radius is 3 m, its area is increasing at a rate of

$\dfrac{\mathrm dS}{\mathrm dt}=8\pi(3\,\mathrm m)\left(\dfrac5{18\pi}\dfrac{\rm m}{\rm s}\right)=\dfrac{20}3\dfrac{\mathrm m^2}{\rm s}$

4 0

3 years ago

Roger has $2, $1 and 50 cent pieces in the ratio of 5:4:2. If 30 of roger’s coins are 50 cent pieces, how many $2 coins and $1 c

rosijanka [135]

Answer:

Step-by-step explanation:

So the ratio is 5:4:2

there are 11 parts to this ratio (5+4+2)

the 5 is for the $2, the 4 is for the $1 and the 2 is for the 50 cents

he has 30 of the 50 cents

so you divide 30 by 2 to get one part of this ratio

1 part of this ratio is equal to 15 coins

multiply 15 by 5 to get the number of $2 coins: 75

multiply 15 by 4 to get the number of $1 coins: 60

add all of those parts together

30+60+75 = 165

If he uses a $1 coin to buy the sundae he will have 75 $2 coins and 59 $1 coins left

however, if he uses two 50 cents coins to buy the sundae he will have 75 $2 coins and 60 $1 coins left

4 0

3 years ago

Read 2 more answers

6. Andy scored 90 on the last history exam. He scored 81 this time. By what percent did his score decrease?

allsm [11]

Answer:

His score decreased by 9 percent this time.

Step-by-step explanation:

From his first history exam he had a score of 90 percent. The difference between his first score and present score is given by

90 - 81 = 9

6 0

2 years ago

The swimming pool at Spring Valley High School is a rectangle with a width of 70 meters and a length of 30 meters. Around the pe

Nadya [2.5K]

The expression for the area of the rectangular swimming pool is given as follows:

A = w² + 100w + 2100.

<h3>What is the area of a rectangle?</h3>

The area of a rectangle of length l and width w is given by the multiplication of these measures, that is:

A = lw.

In this problem, considering the width of 70 meters and a length of 30 meters, plus the floor of w meters, we have that:

l = 30 + w.

wi = 70 + w.

Hence the area is given as follows:

A = l x wi = (30 + w)(70 + w) = w² + 100w + 2100.

More can be learned about the area of a rectangle at brainly.com/question/10489198

#SPJ1

4 0

1 year ago

How do you write 7.75 in scientific notation? i neeeed helps asap!