Monday

April 27, 2015

April 27, 2015

Total # Posts: 1,756

**phy**

[Q1] Note that for an ideal gas, the volume of the gas is directly proportional to the temperature of the gas (Charles' Law). Just think of it as when you have a balloon of certain volume, and then you heated it (temperature increases), the balloon will expand (volume also...
*July 3, 2013*

**chemistry**

Assuming the gas is ideal, we use Charles' Law to relate the relationship between Temperature & Volume of gas: V1/T1 = V2/T2 where: T1 = initial temperature of gas (in K) T2 = final temperature of gas (in K) V1 = initial volume of gas V2 = final volume of gas substituting...
*July 3, 2013*

**chemistry**

Assuming the gas is ideal, we use Charles' Law to relate the relationship between Temperature & Volume of gas: V1/T1 = V2/T2 where: T1 = initial temperature of gas (in K) T2 = final temperature of gas (in K) V1 = initial volume of gas V2 = final volume of gas *note that to...
*July 3, 2013*

**chemistry**

Assuming the gas is ideal, we use Gay-Lussac's Law to relate the relationship between Temperature & Pressure of gas: P1/T1 = P2/T2 where: T1 = initial temperature of gas (in K) T2 = final temperature of gas (in K) P1 = initial pressure of gas P2 = final pressure of gas *...
*July 3, 2013*

**Physics**

Here, CSA of first rod = C CSA of first rod = D Thermal Conductivity of first wire = a Thermal Conductivity of 2nd wire = b Let the length of the two wires be L Temperature difference at the ends be ∆T Now by law thermal conduction for first conductor ∆Q/∆t...
*June 3, 2013*

**math**

Christamas card costs $0.75 each and postage stamps costs $0.39 each. If you have $3.00 only to spend on sending 2 cards to your friends, how much money will be left after sending the cards
*April 24, 2013*

**Chemistry**

N2 + 3 H2 -> 2 NH3 Just use their stoichiometric coefficients (number before the chemical's name) from the balanced chemical reaction to make ratios and solve for the unknown. In this case, 2 moles of NH3 are produced for every 3 moles of H2. Thus, 7.5 moles H2 x (2 ...
*March 18, 2013*

**chemistry**

Divide the mass given in the problem by the atomic weight of Copper from the period table. hope this helps~ :)
*March 11, 2013*

**Math**

First we represent the unknowns: Let x = daughter's present age Let 2x = mother's present age According to the problem, 20 years ago, the mother was three times older than her daughter. Thus, 2x - 20 = 3(x - 20) Solving for x, 2x - 20 = 3x - 60 2x - 3x = -60 + 20 -x...
*March 6, 2013*

**math**

Number of hours spent on studying = 4 Total number of hours (in a day) = 24 Percent of her day spent on studying is equal to: 4/24 * 100 = ? hope this helps~ :)
*March 6, 2013*

**math**

Yup that's right. :)
*March 6, 2013*

**math**

Percent of the theater filled is equal to the number of tickets sold over the total seats: 100/250 * 100 = ? hope this helps~ :)
*March 6, 2013*

**Math**

I think this problem has a figure given, but it can't be shown. Well I think it's ok. Acceleration is equal to change in velocity over time. Note that is a vector quantity, so it is represented by magnitude and direction. In the problem, since it slows down, it is ...
*March 6, 2013*

**Math**

I am a number on the hundreds chart. The sum of my digits is 9. My tens digit is 4. What number am I?
*December 6, 2012*

**physics**

Hello jai. (lol we're using the same name) :p Anyway, I think the statement is wrong that it forgot to mention the direction where the car travels. Velocity is equal to displacement over time, which is a vector quantity, thus it shall be stated using magnitude and ...
*December 4, 2012*

**physics**

Your friend says his remote control car travels at a velocity of 1.5 m/s. What is wrong with that statement
*December 4, 2012*

**algebra**

8y + 7x = -21 8y = -21 - 7x y = -21/8 - (7/8)x
*October 20, 2012*

**math**

C. less than eight
*October 20, 2012*

**General Chemistry**

What is the molality of a solution composed of 38.0 g of cane sugar (C12H22O11) dissolved in 175 g of water?
*September 18, 2012*

**Algebra 2**

14 + 3x – 7 = 7x + 7 – 4x 7 + 3x = 7 + 3x 0 = 0 It is ALWAYS true.
*August 29, 2012*

**Physics**

Tan(b)=31.4 /100
*August 27, 2012*

**Please help quick! Maths**

It's difficult to show here the graphical method, but there are many ways on how to do this. One way is to choose three random values of x (for example, 0, 1, and 2) and get the corresponding y value by substituting these values to both equations, and plot the points on a ...
*August 26, 2012*

**Please help quick! Maths**

It's difficult to show here the graphical method, but there are many ways on how to do this. One way is to choose three random values of x (for example, 0, 1, and 2) and get the corresponding y value by substituting these values to both equations, and plot the points on a ...
*August 26, 2012*

**Please help quick! Maths**

To do substitution method, we choose an equation and express one of the variables in terms of the other, and finally substitute this to the other equation. In this case, let's choose the first given equation and express x in terms of y: x - 2y - 5 = 0 x = 2y + 5 then we ...
*August 26, 2012*

**College Algebra**

1. fog(x) = 2 /[(7/x) - 3] simplifying, 2x/(7 - 3x) Domain: all real numbers except 3, 0 and 7/3 2. 2^(1-9x) = e^(2x) get ln of both sides: ln 2^(1-9x) = ln e^(2x) (1-9x)*(ln 2) = 2x (1-9x)/(2x) = 1/(ln 2) 1/(2x) - 9/2 = 1/(ln 2) 1/(2x) = 1/(ln 2) + 9/2 2x = 1/[1/(ln 2) + 4.5...
*August 14, 2012*

**9th grade math**

3 5/8 - 1 3/4 To do this, first we convert the mixed numbers to improper fractions. To convert we multiply the denominator (the number under the line) by the constant then add this answer to the numerator (number above the line), while retaining the denominator. Doing this, 3 ...
*July 26, 2012*

**algebra**

3x^3 + 9x^2 + 6x 3x(x^2 + 3x + 2) 3x(x+1)(x+2)
*July 25, 2012*

**algebra**

7z^2 + 21z - az - 3a 7z(z + 3) - a(z + 3) (7z - a)(z + 3)
*July 25, 2012*

**chemistry**

Heat of sublimation. It is approximately equal to 2850 J/g H2O.
*July 24, 2012*

**math**

2x(z - 1) + 8x 2xz - 2x + 8x 2xz + 6x
*July 24, 2012*

**math**

-8 1/8 = (6 1/2)p so first, we change the mixed numbers into improper fractions. To convert them, we take the product of the denominator and the constant then add it to numerator. This answer is the new numerator, while retaining the denominator: 8 1/8 = (8*8 + 1)/8 = 65/8 6 1...
*July 17, 2012*

**practical math**

assuming the gas is ideal, we can use the Charles' Law: V1 / T1 = V2 / T2 where V1 = initial volume of gas T1 = initial temp of gas V2 = final volume of gas T2 = final temp of gas substituting the values to the equation, 0.20 / 333 = V2 / 533 V2 = 0.20*533/333 V2 = 0.32 ...
*July 17, 2012*

**Calc**

f(x) = e^(−3x) + 5e^(4x) Note that the derivative of e^x is equal to e^x times the derivative of the exponent with variable x: d/dx (e^x) = e^x dx applying this, f'(x) = -3e^(-3x) + 20e^(4x) : First derivative f''(x) = 9e^(-3x) + 80e^(4x) : Second derivative
*July 17, 2012*

**algebra 117**

i interpreted it as: 3/(x^2 + x - 6) substituting x = 3, 3/(9 + 3 - 6) 3/6 1/2
*July 17, 2012*

**math**

2 log x - log 3 = 2 recall some laws of exponents. Note that we can rewrite the first terms as: 2 log x = log (x^2) Also, when two log terms of the same base are being subtracted, we can rewrite it as the quotient of the terms inside the log: log (x^2) - log (3) = log [(x^2)/3...
*July 17, 2012*

**math**

let x = your age 400 - 2x = 236 400 - 236 = 2x 164 = 2x x = 82
*July 17, 2012*

**Math**

I. 3x + 7y + 5 = 0 4x - 3y - 8 = 0 To solve, we can either use substitution or elimination method. For substitution, we choose one equation and represent one variable in terms of the other. Let's choose the first equation, and represent x in terms of y: 3x + 7y + 5 = 0 3x...
*July 16, 2012*

**math30**

substitute the value: pH = -log[H+] 2.5 = -log[H+] -2.5 = log[H+] note that log has a base of. Thus to get [H+], raise both sides of equation by 10 (to cancel the log): 10^(-2.5) = [H+] [H+] = 3.2 x 10^(-3)
*July 11, 2012*

**algebra**

*I had a correction for the last question you posted: Q: mang pedring wanted to construct a square table such that the length of its side is 30 cm longer than its height. What expression represents the area of the table? Suppose the table is 90 cm high what would be the area? ...
*July 11, 2012*

**Integral math**

Note that the given equation is a parabola that opens upward. The only point on the graph where the tangent line is parallel to the x-axis is at the vertex of the parabola, where it is at minimum. The slope of the tangent line at this point is zero (y=0). To get this point, we...
*July 11, 2012*

**Integrated Math 1**

f(x)g(x)= x^1999 * (2x - x^5) note that to multiply terms with the same base (in this case, the base is the variable x), we just add their exponents: 2*x^(1999+1) - x^(1999+5) 2x^2000 - x^2004 if it's just a typo, the answer is A. :)
*July 11, 2012*

**Integrated Math 1**

f(x) = -1 - 6x^2 - x^3 g(x) = -2 - 4x^2 f(x)-g(x) = -1 - 6x^2 - x^3 - (-2 - 4x^2) -1 - 6x^2 - x^3 + 2 + 4x^2 1 - 2x^2 - x^3 it's A. :)
*July 11, 2012*

**algebra_correction**

*wait. I had a correction: If table is 90 cm high, then the length of square is 120 cm. Substituting this to the equation for area, A = 90^2 + 60(90) + 900 A = 14400 cm^2 *sorry about that! The x value substituted must be 90, not 120. x__x ..haha wow ang galing naman,, fellow ...
*July 11, 2012*

**algebra**

Let x = height of table Let x+30 = length of table Recall that area of square is given by A = L^2 where L = length of one side. substituting, A = (x+30)^2 A = x^2 + 60x + 900 If table is 90 cm high, then the length of square is 120 cm. Substituting this to the equation for ...
*July 11, 2012*

**algebra**

probably the height in the problem is the length of the leg of the table or how high the table is.
*July 11, 2012*

**algebra**

*sorry i mean length = x + 30
*July 11, 2012*

**algebra**

Let x = height of the table since length is 30 cm longer than the height, then height = x + 30
*July 11, 2012*

**trigonometry**

First note that a whole circle measures 360 degrees or 2pi radians. The 3/2pi radians is just 3/4 of 2pi, Thus we can say that the length of arc given (the 60 ft) is just 3/4 of the circumference of the circle. If 60 is just 3/4 of the whole, then 60/(3/4) = 80 ft is the ...
*July 11, 2012*

**algebra**

let x = length of ladder if you draw the figure, you actually form a right triangle, where the ladder is the hypotenuse, and the wall is the height. Thus, we use trigonometry. sin (angle) = opposite / hypotenuse sin 75 = 34 / x x = 34 / (sin 75) x = 34 / 0.966 x = 37.27 ft ...
*June 5, 2012*

**Pre-Calc/Math**

recall that sin^2 x + cos^2 x = 1 therefore, we use this substitute the sin^2 x at the right side of equation: cos(x) + 1 = 1 - cos^2 x cos(x) = -cos^2 x cos(x) + cos^2 (x) = 0 factoring, cos(x) [1 + cos(x)] = 0 *for cos(x) = 0, the x values allowed are π/2 and 3π/2...
*May 23, 2012*

**Math**

Note that slope-intercept form is in the form y = mx + b where m = slope b = y-intercept Thus, y - 3 = -5(x + 1) y = -5x - 5 + 3 y = -5x - 2
*May 23, 2012*

**Math**

recall slope-point form: y - y1 = m(x - x1) where m = slope (x1, y1) = point on the line thus, y - 5 = 2(x - (-1)) y = 2(x + 1) + 5 y = 2x + 2 + 5 y = 2x + 7 hope this helps` :)
*May 23, 2012*

**Math**

recall slope-point form: y - y1 = m(x - x1) where m = slope (x1, y1) = point on the line thus, y - 5 = 2(x - (-1)) y = 2(x + 1) + 5 y = 2x + 2 + 5 y = 2x + 7 hope this helps` :)
*May 23, 2012*

**6th g-math**

let p = number of packs of mech pencil the total amount he could spend is 1.5p + 5.5 and this amount cannot be greater than (but can be equal to) $10, since his only money is $10. Thus, 1.5p + 5.5 _< 10 it's A.
*May 23, 2012*

**Elem Math**

Nope. Multiplying the lengths of sides gives you the volume. To get the surface area of a rectangular prism, SA = 2(L*W + L*H + W*H) where L = length W = width H = height therefore, #1. SA = 2(6*4.25 + 6*3.5 + 4.25*3.5) SA = 122.75 ft^2 #2. SA = 2(4*2.5 + 4*2.33 + 2.5*2.33) SA...
*May 23, 2012*

**Precalculus**

120 degrees and 300 degrees
*May 23, 2012*

**science**

first, write the chemical reaction: NH3 + H2SO4 -> (NH4)2SO4 then we balance this: 2NH3 + H2SO4 -> (NH4)2SO4 then we find the weight of NH3 and (NH4)2SO4. We can do this by getting each atomic mass of the element in the chemical formula, and add them. It can be found on ...
*May 23, 2012*

**trig**

let x = height of tree tan(angle) = x/27 tan(26) = x/27 x = 0.488*27 x = 13.17 = 13 m
*May 23, 2012*

**algebra 1**

(z - 4)/(z + 7) = 1/5 cross-multiplying, 5(z - 4) = z + 7 5z - 20 = z + 7 4z = 27 z = 27/4
*May 23, 2012*

**Geometry**

tan A * tan B = 1
*May 23, 2012*

**math**

sorry, i could not understand #15. #16. you have to plot this. But if you already know some properties of circle (in terms of its equation), you can skip plotting. The equation is a graph of circle, with center at (-6,-4) and radius = 6. The center is the position of source, ...
*May 23, 2012*

**circles**

At first, I was having difficulty understanding the given. I thought the PQ, PR and QR are the lengths of the triangle, but they are actually the arc (angle measure). Anyway, to get x, we know that the measure of a circle is 360 degrees. We get the sum of arcs PQ, PR and QR ...
*May 23, 2012*

**math**

3.62 x 10^7
*May 23, 2012*

**circles and arcs**

At first, I was having difficulty understanding the given. I thought the PQ, PR and QR are the lengths of the triangle, but they are actually the arc (angle measure). Anyway, to get x, we know that the measure of a circle is 360 degrees. We get the sum of arcs PQ, PR and QR ...
*May 23, 2012*

**chemistry**

recall that one mole of any substance is equal to Avogadro's number, which is 6.02 x 10^23 this number can be atoms, molecules, ions, etc. to get the number of moles, we just divide the given by the Avogadro's number: 2.8 x 10^20 / 6.02 x 10^23 = ?
*May 23, 2012*

**algebra**

[-16(x^7)(y^4)z]/[20(x^2)(z^3)] -4(x^5)(y^4)/(5z^2)
*May 23, 2012*

**PHYSICAL SCIENCES**

A. Argon all noble gases, except Helium, has eight valence electrons.
*May 23, 2012*

**MATHS**

that is true, if 'ln' is used, not 'log'. Well, in some books, ln and log seem interchangeable -they really mean ln, not log. If we rewrite the expression using ln, not log, e^(x + 3lnx) we can separate this into: (e^x)[e^(3lnx)] note that we can further ...
*May 23, 2012*

**math**

*sorry i mean x = 3/4
*May 23, 2012*

**math**

6 = 4x + 3 6 - 3 = 4x 3 = 4x x = 4/3
*May 23, 2012*

**maths**

work backwards: 2(2(2(2(0+1)+1)+1)+1) = 30 liters
*May 22, 2012*

**Math**

525
*May 22, 2012*

**Math**

let x = age of Travis let x-4 = age of Ellie (since Travis is four years older than Ellie) let 2(x-4) = age of Mac (since he is twice older than Ellie) since the sum of their ages is 44, x + x - 4 + 2(x - 4) = 44 2x - 4 + 2x - 8 = 44 4x - 12 = 44 4x = 56 x = 14 yrs old (Travis...
*May 22, 2012*

**Math**

recall that volume of cone is given by V = (1/3)*pi*(r^2)*h where r = radius which is half of diameter h = height and pi = constant equal to 3.14 substituting, V = (1/3)*3.14*[(5/2)^2]*7 now solve for V.
*May 22, 2012*

**math algebra**

let x = first number let x+1 = second number let x+2 = third number let x+3 = fourth number *note that there is +1 for every number since they are consecutive. therefore, x + x+1 + x+2 + x+3 = -2 4x + 6 = -2 4x = -8 x = -2 x+1 = -1 x+2 = 0 x+3 = 1 hope this helps~ :)
*May 21, 2012*

**math trig**

ln(2x-5) = 4 we raise both sides by e: e^(ln(2x-5)) = e^4 the e and ln will be cancelled, leaving only the 2x - 5: 2x - 5 = e^4 2x = e^4 + 5 x = (e^4 + 5)/2 hope this helps~ :)
*May 21, 2012*

**math**

Oh sorry. I thought it's outside. Nope, it can't be moved outside. 2^(x+1) = 9 2^(x+1) = 3^2 then we take the log of both sides: (x+1)*(log 2) = 2*(log 3) x + 1 = 2(log 3) / (log 2) x = [2(log 3) / (log 2)] - 1 or we can also rewrite the 1 as (log 2)/(log 2), so x = [2...
*May 21, 2012*

**math**

2^x + 1 = 9 2^x = 9 - 1 2^x = 8 then we rewrite 8 as power of 2: 2^x = 2^3 finally, since they have the same base (which is 2) we equate their exponents: x = 3 hope this helps~ :)
*May 21, 2012*

**math**

No. First to multiply fractions, we change mixed number into improper fraction. The mixed number here is 1 1/4. To change this, we multiply the denominator (the 4) to the constant (the first 1, not the 1 above the bar line) and add this to numerator. thus, 1 1/4 = (1*4 + 1)/4...
*May 21, 2012*

**maths**

recall these properties: -all sides of rhombus are equal. -the diagonals of rhombus are perpendicular (forms four 90 degree angles) -area of rhombus, if diagonals are given, can be calculated by A = d1 * d2 /2 where d1 & d2 are the diagonal lengths -side of a rhombus, if ...
*May 21, 2012*

**maths**

I think it has a typo. (what is "1nd")
*May 21, 2012*

**algebra**

for this problem, we will substitute the given to the equation p = mx + b, and then we solve simultaneously (two equations, two unknowns): 25 = 56m + b 20 = 66m + b to solve this, we can multiply one equation by -1 so that if we add the equations, the b will be cancelled: -25...
*May 21, 2012*

**maths**

let x = first number let 8-x = second number then we set up the equation. It says that the sum of their squares must be 34. thus, x^2 + (8-x)^2 = 34 then we solve for x: x^2 + 64 - 16x + x^2 = 34 2x^2 - 16x + 64 = 34 2x^2 - 16x + 30 = 0 x^2 - 8x + 15 = 0 since it's ...
*May 21, 2012*

**maths**

recall that an isosceles triangle has two equal sides. thus, to find this length, recall that the perimeter of a triangle is given by P = a + b + c but since two sides are equal, we can rewrite this as P = 2a + c substituting, 32 = 2a + 12 20 = 2a a = 10 now to find the area, ...
*May 21, 2012*

**Geometry**

recall that the volume of an oblique cone is given by V = (1/3)*(πr^2)*h where r = radius of circle (the base) h = height since diameter is equal to the height, we can say that h = d = 2r substituting, V = (1/3)π(r^2)(2r) 18π = (2/3)π(r^3) 18*(3/2) = r^3 27...
*May 21, 2012*

**Algebra (re: %)**

60/70 * 100 = 85.7%
*May 21, 2012*

**Trigonometry**

To combine the two log terms, first, the terms must have the same base (the number subscript of log). In this case, if there is no number subscript of log, the base is equal to 10. The two terms have the same base, 10. Now, recall that to combine log terms of the same base, *...
*May 19, 2012*

**math**

Let x = length of side of square thus area of square is A,square = x^2 recall that area of triangle is given by A,triangle = (1/2)b*h where b is the base and h is the height. The base and height of the triangle AMN are equal, which is (1/2)x. Thus, A,triangle = (1/2)*[(1/2)x...
*May 19, 2012*

**algebra.**

let x = width let 6x = length (according to the first statement) recall that area of a rectangle is given by, A = length x width thus, 54 = x * 6x 54 = 6x^2 9 = x^2 x = 3 ft (width) 6x = 18 ft (length) hope this helps~ :)
*May 18, 2012*

**math**

I think you mean, the ratio of the lengths of the smaller and larger cube. Recall that the surface area of a cube is given by SA = 6s^2 where s = length of one side then we get the length of one side of each cube. Larger: 32 = 6s^2 16/3 = s^2 s = 4/sqrt(3) Smaller: 18 = 6s^2 3...
*May 17, 2012*

**math**

I think you mean, the ratio of the lengths of the smaller and larger cube. Recall that the surface area of a cube is given by SA = 6s^2 where s = length of one side then we get the length of one side of each cube. Larger: 32 = 6s^2 16/3 = s^2 s = 4/sqrt(3) Smaller: 18 = 6s^2 3...
*May 17, 2012*

**chemistry**

first we write the chemical equation: C6H6 + O2 -> CO2 + H2O then we balance this: 2C6H6 + 15O2 -> 12CO2 + 6H2O then we solve for the molecular weight of C6H6. Note that mass of C = 12 and H = 1. thus, 6*12 + 6*1 = 78 g/mol then we get the number of moles of C6H6 used in...
*May 16, 2012*

**chemistry**

first we write the chemical equation: C6H6 + O2 -> CO2 + H2O then we balance this: 2C6H6 + 15O2 -> 12CO2 + 6H2O then we solve for the molecular weight of C6H6. Note that mass of C = 12 and H = 1. thus, 6*12 + 6*1 = 78 g/mol then we get the number of moles of C6H6 used in...
*May 16, 2012*

**Geometry**

*i mean 56 degrees.
*May 16, 2012*

**Geometry**

it's difficult to show solutions (because diagrams are required), but my answer is 58 degrees.
*May 16, 2012*

**Chemistry**

H2 + O2 -> H2O balancing this, 2H2 + O2 -> 2H2O then we find the limiting reactant. To determine the limiting reactant, we get the moles of product from the given moles of reactant. Whichever yield less number of moles of product is the limiting reactant. thus, 4 mol H2...
*May 16, 2012*

**Math**

270 degrees
*May 15, 2012*

**math**

(2x-5)/6 = (4x+1)/2 we must make the denominators same. to do this, we multiply the numerator & denominator of the term on the right by 3: (2x-5)/6 = 3(4x+1)/6 then we equate the numerators: 2x - 5 = 12x + 3 2x - 12x = 5 + 3 -10x = 8 x = -4/5
*May 15, 2012*

**math 8th grade**

multiply the given dimensions: 4 * 12 = 36 5 * 11 = 55 7 * 9 = 63 8 * 8 = 64 therefore, it's 8 in x 8 in.
*May 14, 2012*

**math 8th grade**

recall that area of rectangle (shape of the photo) is given by A = length * width substituting, A (original) = 3 * 5 = 15 if we triple both length and width, new length = 3 * 5 = 15 new width = 3 * 3 = 9 thus, A (new) = 15 * 9 = 105 to get the ratio, we divide the new area by ...
*May 14, 2012*