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# Mathematics

## Discover

- 16Upvotes of all answers in this question
### Convert the whole number to a percent: 58?

19 Answers6 days ago - 9Upvotes of all answers in this question
- 2Upvotes of all answers in this question
### Help with this math question?

Determine which of the following matrix equations represents the solution to the system:

2x + y = 2

5x + 3y = 13.

8 Answers4 days ago - 5Upvotes of all answers in this question
### How do you solve this math word problem? PLEASE HELP ME AND EXPLAIN STEP BY STEP!!!?

A lumberyard charges $ 1 per cut to trim boards. Bob buys a 12-ft board and wants it out into twelve 1-ft pieces. How much will he be charged for the cutting? The correct answer is $11.

9 Answers5 days ago - 3Upvotes of all answers in this question
### Am I right?

Hello, I'm 14 years old, I'm currently in 8th grade and I'm practicing math so answer here if I'm right.

X + X = 2X

X × X = X²

X + Y = XY

6 Answers4 days ago - 6Upvotes of all answers in this question
### which set of values for x should be tested to determine the possible zeros of y = x^3 + 6x^2 - 10x + 35? (multiple choice)?

Favorite Answer:It's a cubic equation...

so possible zeros are when

0 = (x-a)(x-b)(x-c)

==> 0 =x^3 -(a+b+c)x^2 + (ab + ac+bc)x -abc

so

-a*b*c = 35

factoring 35... one of the factors must be negative

So, looking at absolute values

|1| * |1| * |35|

|1| * |5| * |7|

so c) is not right -- 12 is not among the factors above

d) is not right -- one of the factors must be possibly negative

a) is out, since one of the factors must be 1 or -1

which leaves b) as the answer

5 Answers4 days ago - 7Upvotes of all answers in this question
### Can someone help me with this equation? Reducing to linear form using logs?

Favorite Answer:If you've worked it out, I think you should have posted your work and then asked for someone to review it. Otherwise it looks like you just want someone else to do the work.

In any case, I'll do my best to help.

Original equation:

T = 2π√(l/g)

Take the log of both sides:

log(T) = log[2π√(l/g)]

Use the product rule to turn the log of a product in a sum of logs:

log(T) = log(2) + log(π) + log[√(l/g)]

Looking at the third log, we know that a square root can be rewritten as raising something to the ½ power:

log(T) = log(2) + log(π) + log[(l/g)^½]

Using the power rule, we can bring ½ to the front:

log(T) = log(2) + log(π) + ½ log(l/g)

Finally, use the quotient rule to split the last log into a subtraction of logs.

log(T) = log(2) + log(π) + ½[log(l) - log(g)]

5 Answers4 days ago - 1Upvotes of all answers in this question
### The solution an algebraic equation.?

Favorite Answer:It would be useful to memorize the following:

lim (1 + 1/x)^x = e

x→∞

let x = n/r

(1+r/n)^(nt) = (1 + 1/x)^(xrt)

= ((1 + 1/x)^(x))^(rt)

lim ((1 + 1/x)^(x))^(rt) = e^(rt)

x→∞

Thus

2P = Pe^(rt)

t = ln(2)/r

Because ln(2) is approximately 70% (and less-frequent compounding increases t), this leads to the "Rule of 72": for a given rate of return r%, your investment will double in approximately 70/r or 72/r years.

4 Answers3 days ago - 30Upvotes of all answers in this question
- 2Upvotes of all answers in this question
### Could you please help me with this mathematical problem?

Favorite Answer:given

t = 1 min x 1hour/60min = 0.0166 hours

d = 50 m x 31 = 1550 m x km/1000m = 1.55km

solving the trains speed

s = d/t

s = 1.55 km/ 0.0166 hours

s = 93.37 km/h or 93 km/h Answer//

4 Answers4 days ago - 5Upvotes of all answers in this question
### what is 3/2 of 4?

11 Answers1 week ago - 1Upvotes of all answers in this question
### Finding the equation of the normal to the curve?

5 Answers6 days ago - 2Upvotes of all answers in this question
- 2Upvotes of all answers in this question
### Math questions ?

Favorite Answer:Are all the question weighted equally? Are all the questions equally difficult?

75 minutes * 60 seconds = 4500 seconds

If you divide that total time by 128 questions, you get the average per question.

4500 / 128 ≈ 35 seconds / question

4 Answers5 days ago - 3Upvotes of all answers in this question
### Find the sum of the infinite series below?

4 Answers5 days ago - 0Upvotes of all answers in this question
### Finding Derivative of a Point?

Favorite Answer:g(x) = 4x² - 2x + 15 ← this is a function

g(5) = 100 - 10 + 15 = 105 → the representative curve of the function passes through (5 ; 105)

g'(x) = 8x - 2 ← this is its derivative

g'(5) = 40 - 2 = 38 ← this is in fact the slope of the tangent line to the curve at point (5 ; 105)

g(x) = 4x² - 2x + 15 ← this is the function → to calculate the derivative:

Lim [g(x₀ + h) - g(x₀)] / h

h → 0

Lim [ { 4.(x₀ + h)² - 2.(x₀ + h) + 15 } - { 4x₀² - 2x₀ + 15 } ] / h

h → 0

Lim [ { 4.(x₀² + 2x₀.h + h²) - 2x₀ - 2h + 15 } - 4x₀² + 2x₀ - 15 ] / h

h → 0

Lim [4x₀² + 8x₀.h + 4h² - 2x₀ - 2h + 15 - 4x₀² + 2x₀ - 15] / h

h → 0

Lim [8x₀.h + 4h² - 2h] / h

h → 0

Lim h.[8x₀ + 4h - 2] / h

h → 0

Lim (8x₀ + 4h - 2) = 8x₀ - 2

h → 0

g'(x₀) = 8x - 2

g'(5) = 40 - 2 = 38 ← this is the same result (above)

4 Answers1 week ago - 1Upvotes of all answers in this question
### Solve the system: y=14x2+2x−6 y=−14x2−3x+6?

The parabolas above intersect in two places, at (a , b) and (c , d), where a, b, c, and d are all integers. a + b + c + d =

7 Answers1 week ago - 20Upvotes of all answers in this question
- 5Upvotes of all answers in this question
### find the sum of (7t + 6 ) + (-4t -2)?

Favorite Answer:Remove the brackets

Hence

7t + 6 +-4t +-2

Remember +/- becomes minus (-)

7t + 6 - 4t - 2

3t + 4

Done!!!!

Remember for +/- double signs .

+ + = +

+ - = -

- + = -

- - = +

If no sign is given read it as plus(+).

6 Answers1 week ago - 5Upvotes of all answers in this question
### 4^x-2=3 How do I solve this and round my answer 3 places past the decimal?

9 Answers1 week ago