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3 years ago

I really need help on this, I don't quite understand what I am doing :.)

Mathematics

1 answer:

enot [183]3 years ago

4 0

Subtract the two equations

f(x) - g(x)

(9x3 + 2x2 - 5x + 4) - (5x3 - 7x + 4)

9x3 + 2x2 - 5x + 4 - 5x3 + 7x - 4

4x3 + 2x2 + 2x

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an inlet pipe and a hose together can fill the pond in 10 hours. The inlet pipe alone can complete the job in one hour less time

Annette [7]

Answer:

The hose pipe can fill the pond in 21.465 hours.

The inlet pipe can fill the pond in 20.465 hours.

Step-by-step explanation:

Given that, a inlet pipe and a hose pipe together can fill the pond in 10 hours.

The inlet pipe alone can fill the pond in one hour less time than the hose pipe can fill the pond.

Let the hose pipe can complete the job in x hours.

Then the inlet pipe can fill the pond in (x-1) hours.

The rate of filling of hose pipe is $=\frac{1}{x}$

The rate of filling of inlet pipe is $=\frac{1}{x-1}$

The rate of filling of both pipes is = $\frac 1{10}$

According to the problem,

$\frac{1}{x}+\frac{1}{x-1}=\frac{1}{10}$

$\Rightarrow \frac{x-1+x}{x(x-1)}=\frac1{10}$ [ simplifying the fraction]

$\Rightarrow \frac{2x-1}{x^2-x}=\frac1{10}$

$\Rightarrow 10(2x-1)= x^2-x$ [ Multiplying 10(x²-x) both sides]

$\Rightarrow x^2-x= 20x-10$

$\Rightarrow x^2-x-20x+10=0$ [ simplifying ]

$\Rightarrow x^2-21x+10=0$

$\Rightarrow x=\frac{-(-21)\pm\sqrt{(-21)^2-4.1.10}}{2.1}$ [ applying quadratic formula]

$\Rightarrow x=\frac{21\pm21.93}{2.1}$

⇒ x= 21.465, -0.465

x= - 0.465 does not possible, since time can not be negative.

∴x=21.465

The hose pipe can fill the pond in 21.465 hours.

The inlet pipe can fill the pond in (21.465-1)=20.465 hours.

3 0

3 years ago

HELP jedimasterkidz please here is their question

Alex73 [517]

Answer: Okay I think D is the answer

Step-by-step explanation:

4 0

3 years ago

Read 2 more answers

Prove that every integer greater than 7 can be written by using 3's and 5's only. that is, for every n > 7 there exist non-ne

Taya2010 [7]

An integer may be a multiple of 3.
An integer may be 1 greater than a multiple of 3.
An integer may be 2 greater than a multiple of 3.

It is redundant to say an integer is 3 greater than a multiple of 3 (that's just a multiple of 3, we've got it covered). Same for 4, 5, 6, 7...

Let's consider a number which is a multiple of 3. Clearly, we can write 3+3+3+3+... until we reach the number. It can be written as only 3's.

Let's consider a number which is 2 greater than a multiple of 3. If we subtract 5 from that number, it'll be a multiple of 3. That means we can write the number as 5+3+3+3+3+... Of course, the number must be at least 8.

Let's consider a number which is 1 greater than a multiple of 3. If we subtract 5 from that number, it'll be 2 greater than a multiple of 3. If we subtract another 5, it'll be a multiple of 3. That means we can write the number as 5+5+3+3+3+3+... Of course, the number must be at least 13.

That's it. We considered all the numbers. We forgot 9, 10, 11, and 12, but these are easy peasy.

Beautiful question.

4 0

3 years ago

(4x+ 1) - 3i = 2+ (3y + 5)i

Vesna [10]

(4x+1)-3i= 2 +(3y+5)i

3 0

3 years ago

Can anyone help me on this problem? Please it doesn’t make sense to me...

Sav [38]

Answer:

Step-by-step explanation:

Cost per item is found by dividing the cost by the number of items. If the woman bought n items for $120, the cost of each item is $120/n. If the woman bought 24 more items, n+24, at the same price, then the cost per item is $120/(n+24). The problem statement tells us this last cost is $16 less than the first cost:

120/(n+24) = (120/n) -16

Multiplying by n(n+24) gives ...

120n = 120(n+24) -16(n)(n+24)

0 = 120·24 -16n^2 -16·24n . . . . . . subtract 120n and collect terms

n^2 +24n -180 = 0 . . . . . . . . . . . . . divide by -16 to make the numbers smaller

(n +30)(n -6) = 0 . . . . . . . . . . . . . . factor the quadratic

The solutions to this are the values of n that make the factors zero: n = -30, n = 6. The negative value of n has no meaning in this context, so n=6 is the solution to the equation.

The woman bought 6 items.

_____

Check

When the woman bought 6 items for $120, she paid $120/6 = $20 for each of them. If she bought 6+24 = 30 items for the same money, she would pay $120/30 = $4 for each item. That amount, $4, is $16 less than the $20 she paid for each item.

3 0

3 years ago