Sunday
April 20, 2014

Posts by Quidditch


Total # Posts: 494

Algebra
For the first problem: Let x = lesser number let y = greater number (x) (y) = 273 The problem states that y = x + 8. substituting for y: (x) (x+8)=273 x^2 + 8x=273 so x^2 + 8x - 273 = 0 Solve for x. Then, y = x + 8

Algebra
Uh-oh, You need to reverse the inequality sign when you multiply or divide both sides by a negative number! should be: y < (1/3)x + 5

Math
Take your step: x^2 + 5x + 6 = 90 Now: x^2 + 5x - 84 = 0 Factor by inspection or use the quadratic formula to solve for x. A hint is what two factors of 84 differ by 5?

Algebra, PLEASE help!
One approach is to just use the quadratic formula to solve it. But, you could probably do it by inspection if you write the equation as: 0.25x^2 + 0.3x + 0.09 =(10^(-2))(25x^2 + 30x + 9)

Algebra
What do you think the answer is?

math
One method: Use substitution to express an equation in one unknown. Choose a. From the first equation... a + b = 6 So, b = 6 - a From the third equation... c + a = 7.5 So, c = 7.5 - a Now write the second equation substituting the values for b and c in terms of a: b + c = 20 F...

Calc help
Just to be clear, it is a vertical line at x=1.

Calc help
Below assumes: y = e^2x means e^(2x) and y = e^5x means e^(5x) The two curves (equations) intersect at x=0, y=1. Then, going in the positive x direction, they diverge. But, the right side of the region is bounded by a line at x=1. So, find the area from x = 0 to x = 1 under th...

Math 116
1. m/n = 8 is correct. 2. x=2178 is not correct 11x=198 divide both sides by 11 x=198/11 x=?

Algebra
Area = length * width length = (2x-1)m width = (x+2)m Area = (2x-1)(x+2) m^2 Multiply the two factors (use FOIL).

Algebra
Let A=Total amount of the stronger (75%) DeMuggle juice potion added in ml. The percent of DeMuggle juice is: (total DeMuggle juice)/(total volume of potion) The final total DeMuggle juice is: 2000ml(30%) + A(%75) =600ml + 0.75A The final total volume of potion is: 2000ml + A ...

Pre Calc
Absolute values are always positive. For any t, |3t| will be larger than |2t| . So, the right side is always negative. The absolute value of the left side is always positive.

math
I think Chopsticks misread the problem. let P=price 20 years ago 49 cents = 4P-(3 cents) 52 cents = 4P P=13 cents

math
let R = rainfall last year in cm. 18.6cm = (R/2) -3.2cm 21.8cm = R/2 R= ?

math
Chopsticks is wrong. let W = Juan's weight in kg 6W - 12kg = 486kg 6W = 498kg W = ?

Math 012
Your are on the right track. You want to get just the variable on one side of the equation. You have done that. Your last step above: 4 - 10 = 10n + 10 - 10 The +10 and - 10 on the right cancel 4 - 10 = 10n Subtract 10 from 4 on the left. Then you something on the left = 10n. ...

Factor Completely
Sorry, I am not sure what they are asking. Someone else here might understand it.

Factor Completely
Is the problem c^2 - 8c + 16 - y^2 = 0?

Factor Completely
OK, (3x^3 - 1) (2x^3 + 5) First Multiply the first terms of the two factors: (3x^3)(2x^3) = 6x^6 Outer Multiply the outer terms of the factors: (3x^3)(5) = 15x^3 Inner Multiply the inner terms of the factors: (-1)(2x^3) = -2x^3 Last Multiply the last terms of the factors: (-1)...

Factor Completely
Yes. Also, lyne mentioned checking using FOIL (First Outer Inner Last). That is a good acronym for multiplying binomials.

Factor Completely
Your step 3: 6u^2 + 13u - 5 What number multiplied give -5? One possibility... (?u - 1) ( ?u + 5) What numbers multiplied give 6? One possibility... (3u - 1)(2u + 5) Now substitute back for u.

calculus
Hint: get rid of the denominator (4x^2 + 10)/(x^(1/2)) =4x^(3/2) + 10x^(-1/2)

math- logarithms
Check your previous post for the solution to problem 2.

math
The first line above (where the problems was restated) should have been: 3^(x^3)=9^x The rest of the lines are correct.

math
For problem 2: 3^(x^3)=9^3 take log of both sides (x^3)log(3)=(x)log(9) divide both sides by x (x^2)log(3)=log(9) 9=3^2 so (x^2)log(3)=2log(3) divide both sides by log(3) x^2=2 x=sqrt(2)

MATH
[SQRT(2x^2 + 5x +6) = x square both sides 2x^2 + 5x + 6 = x^2 subtracting x^2 from both sides... x^2 + 5x + 6 = 0 Factor by inspection or use the binomial theorem to solve for x. The second problem is similar.

math
7x + 13x = 140 Combine all the x terms: 20x = 140 Solve for x.

6th grade Math
night 1=1 night 2=5 night 3=14 night 4=30 difference from 1 and 2 = 4 difference from 2 and 3 = 9 difference from 3 and 4 = 16 Do you see anything special in the differences?

math
First convert the number to a decimal number. Remember that percent is expressed in "hundredths". So multiply the decimal number by 100 to get the percent value. Example: 3 1/16 = 3.0625 = 306.25 percent = 306.25%

Math
Yes, it is correct.

Physics 12
Disregard my answer. I assumed that the stationary block was fixed. I don't think that is the case. DRWLS has the correct approach. He is very good.

Physics 12
K1=initial kinetic energy K2=kinetic energy after collision K1 = (1/2)(5.2kg)(9.4m/s)^2 K2 = (1/2)(5.2kg)(1.80m/s)^2 kinetic energy lost is: K1 - K2

Math
If you can't quickly factor the equation, it is generally easier to just use the quadratic equation. As you do more and more, you will probably remember how you factored them previously.

math [ i need help with these.]
The line -0(3) should have been =0(3) See below: For x=0 2x(x+3) =2(0)(0+3) =0(3) =0

math [ i need help with these.]
2x(x+3)=0 I am assuming that you need to find the values of x that will be true for the above. When you multiply several items (each of these is called a factor) together the answer (called the product) is 0 if ANY of them are 0. Example: multiply (a)(b)(c) If any of them, a o...

math [ i need help with these.]
Sorry, I meant to say factor not term. If any "factor" in a product is 0 the whole product is 0. There are 2 "factors".

math [ i need help with these.]
2. 2x(x+3)=0 There are 2 terms: 2x and (x+3). If any term in a product is 0 the whole product is 0. So, what value of x would make 2x=0 and what value of x would make x+3 = 0?

math
x * y = 7 x - y = 5 One method: express one variable in terms of the other variable and then solve the single variable expression. If x - y = 5 then y = x - 5 substituting back into the first equation: x * (x - 5)=7 Solve for x, then substitue the x value into either equation ...

statistics
Answered in your 5:50pm post.

math
Jessica's answer is not correct. x intercept point = -4,0 y intercept point = 0,2 y = mx + b is the standard line equation where: m = the slope of the line b = the y intercept The problems gives the y intercept as 2. slope = (delta y)/(delta x) = (0 - 2)/(-4 - 0) = -2/(-4)...

Calculus
sorry for the mistake (d g(x)/dx = -6(x^5) SIN (x^6)

Calculus
(d(cos(u))dx = -sin(u)(du/dx) for g(x)=cos(x^6) (d g(x))/dx = -6(x^5)cos(x^6)

Calculus
Close, but I believe is should be: 309(t^2)((t^3)+8)^102

pre calc
N = number of nickles D = number of dimes = N+4 Q = number of quarters = 25-N-D = 25-N-(N+4) = 21-(2N) Add the coins to get $3.20 (N*$0.05) + (D*$0.10) + (Q*$0.25) = $3.20 Expressing D and Q in terms of N: (N*$0.05) + ((N+4)*$0.10) + (21-2N)*$0.25=$3.20 Solve for N. Then plug ...

algebra/math
Check the reply to your 1:15am post.

algebra/math
FOIL is an acronym for First Outer Inner Last used when multiplying binomials. 1. Multiply the FIRST terms in each binomail. In this problem that would be x^(1/2) * x^(1/2) 2. Multiply the OUTER terms: x^(1/2) * 4 3. Multiply the INNER terms: -2 * x^(1/2) 4. Multiply the LAST ...

7th grade
Multiplication is distributive over addition. Division can be performed by multiplying by the inverse of the divisor. So, yes, division is distributive over addition.

physics
Here the vector angles are relative to the X axis. So, east would be 0 degrees, north is 90 degrees, west is 180 degree, and south is 270 degrees. So, SE is 270 + 45 = 315. -45 degrees could also be used.

physics
Break the 3 vectors into components and solve for the unknown vector. For this choose North is positive y East is positive x First vector, 2.00km east represented by (2.00km)x + 0(km)y Second vector, 3.50km SE represented by (3.50)(cos(315))(km)x + (3.50)(sin(315))(km)y Third ...

Help!
Let x = first number Let y = second number x +(2x-1) = y 3x-1=y so x = (y+1)/3

Help!
3 - 8 difference = 5 4 - 11 difference = 7 5 - 14 difference = 9 etc. In each case the difference is: 2 x (first number) - 1

math
Let x be the number. (1/3)(x) + 5 = -2 multiply both sides by 3: x + 15 = -6 subtract 15 from both sides to solve for x.

Math
You are CORRECT on #2. Also There is no parenthesis in the problem. I copied it down and added it.

Math
I got the same for #1. For #2 (-6)^-2 =1/((-6)^2) =1/(36

physics please help!
A handy equation for an object with 0 initial velocity and constant acceleration is: v^2 = (2*a*s) where v = final velocity a = acceleration (in this problem it is gravity) s = distance

Physics
Passenger height = 2.5m + vt = 2.5m + (2.2m/s)t Camera height = (11.6m/s)t + (1/2)(-g)t^2 The camera reaches the passenger when Passenger height = Camera height solve t for equal height, then plug t into either equation for the height. You will find 2 answers for equal height....

Math
For the problem (4m-7)/2 = 18 To solve for m: The object is to get a single m on one side of the equation. 1. get rid of the denominator (2) on the left side by multiplying both sides of the equation by 2. That gives: 4m-7 = 36 Now add 7 to both sides to get just a term with n...

physics
Paint thickness multiplied by area covered should equal the volume of paint. Let T = thickness of paint. T = (volume of paint) / (area covered) T = (231 in^3) / (450 ft^2) Convert 450 ft^2 to its equivalent in in^2, divide, and you have the answer in inches.

math
Check the answer for the similar problem you posted. It is solved the same way.

math
For the problem, a value of x which makes a factor 0 is a solution. (x^2-9)(2x-1) = 0 factoring (x^2-9) further (x+3)(x-3)(2x-1) = 0 For each factor, what value of x will make the term 0? The first term, (x+3), will be 0 for x=-3. The second term is 0 for x=? The third term is...

Math - Imaginary Numbers
Remember that i^2 = -1 3(-2i)^2 =3(-2)^2(i^2) =? -i(isqrt(5))^2 =-i(i^2)(sqrt(5))^2 =?

Math - Imaginary Numbers
Remember that i represents the square root of (-1). So, i^2 = -1 i^5 = (i^2)(i^2)(i) =(-1)(-1)(i) =?

discrete math
Multiply out all the terms -4(k-2) + 3(k+1)=7 -4k + 8 + 3k + 3 = 7 Now combine like terms (all k's and all numbers) -1k + 11 = 7 11 - 7 = k So, k = ?

6th grade
The volume of the hole will be the length X width X depth. It's always good to be sure that units for each dimension are the same. In this problem, they are all in meters. Volume = length X width X depth Volume = 6m X 2m X 1m Multiply the right side to get the volume. Reme...

math
Let B = the number of balloons in each bag. The problem says that each bag has the same number of balloons. Also, after all the bags are used, 18 more balloons are still needed to get to 138. The equation would be: 5B + 18 = 138 To solve for B first subtract 18 from each side:...

math
To clarify the previous posting Number, Square Root: 9, 3 16, 4 23, 4.796 (approximately)

math
The square root of a number is the number which multiplied by itself results in the original number. Number Square Root 9 3 16 4 23 4.796 (approximately) There are methods to calculate the square root without a calculator, but they are a bit involved. google: calculating squar...

Check Work (Math)
That is correct!

MAth
Your answer for the first question (b) is correct. I don't think you copied the second question correctly.

Algebra1
Let's look at this: The original value is 18/7. You want to find an equivalent value that has a denominator of 28. To get that value, you need to multiply the denominator by 4. To "multiply by 1" to not change the value, you need to also multiply the numerator by...

Math
(x+4)log3 = (x+2)log5 (x+4)(0.47712) = (x+2)(0.69897) 0.47712x + 1.90848 = 0.69897x + 1.39794 0.22185x = 0.51054 x=2.301 Checking you will probably find a small rounding error. If you carry the calculations to a lot of decimal places it will be more exact.

PRECALC
See reply to your 6:51pm posting below.

Precalc
Oops! An error on my part! The last line should be: =((2y+7)^5)x((y-2)^4)x[5x(2y+7)+6x(y-2)x2]

Precalc
I changed the variable to y to avoid confusion with the x used for multiplication. [(2y+7)^6 x 5(y-2)^4] + [(y-2)^5 x 6(2y+7)^5 x 2] (2y+7)^5 and (y-2)^4 are common to both terms. bring the common factors outside: =((2y+7)^5)x((y-2)^4)x[(2y+7)+(y-2)x2] There are 2 terms in the...

Algebra
There is an error in the second line. Should be: 10x - 35 < -8

Math Urgent
square both sides, collect like terms and solve. Here's the first step: (k+3)^2 = (2k-1)^2 k^2 + 6k + 9 = 4k^2 - 4k + 1 Combine all the like terms. You might factor it out, but I would suggest using the quadratic equation.

Math Urgent
I don't think you copied the first question correctly. Did you intend 2 equal signs?

Math Urgent
Also, because of the (p+1) term remember that p=-1 will be a solution.

Math Urgent
Hint. Each term on both sides has a factor (p+1). Divide all terms on both sides by (p+1). This will simplify it for you.

Algebra
(x + a ) (x + b) = x^2 + 7x + 10 Think what two number multiplied give 10, and when added give 7?

algebra
let x = speed of first part of trip in mph let x-5 = speed of second part of trip in mph 5 hours = 63 miles/x + 6/(x-5) Solve for x. If you solve a quadratic, ignore the answer which would cause the slower speed to be negative (non-real case).

Calculus
point A f(x) = 1/(x^2) point B f(x+deltaX) = 1/((x+deltaX)^2) The slope of the line between these points is: [f(x+deltaX) - f(x)]/[(x+deltaX - x] The slope of the tangent is given when deltaX->0. to get you started... [(1/(x+deltaX)^2) - 1/x^2]/[x+deltaX - x] Get rid of the...

C++
First problem I see is in your first case 'Yes'. You output "Does the hard drive spin?", then you have a "break;". The break takes you out of the first enclosing switch. So, the cin does not get executed. This same error is in the first case 'No...

Algebra
when you write: (sqrt5/15) Which do you mean: sqrt(5/15) or (sqrt(5))/15

Algebra
If you let y=x^2 then: 25*y^2 - 20*y +3 = 0 You can use the quadratic formula to solve. Your solution for y will really be for x^2. Take the square root of y values to get the x values. I did not get any imaginary values. One answer (that I got) IS sqrt(3/5), but as a real num...

Algebra
That's the answer I got.

math
Calculate the total cost of each game including tax--remember that 8.125% = 0.08125 total cost = game + tax = $3.95 + 0.08125($3.95) Now divide the money he has ($20.92) by the total cost per game. Disregard any remainder/fraction/decimal of a game since you cannot normally pu...

Algebra
For the equation of a line in the form: y = m*x + b m=slope b=y intercept The lines will be parallel if the slopes (m value) are the same. Rearrange the equations to the above form and check for m being the same value for each.

Algebra 1
Correct!

Algebra
Generally, the rational expression will be undefined when the denominator is 0. Find all values for z which would result in the denominator being 0.

College Algebra
For: Assume all values are in inches. L=length of rectangle W=width of rectangle P=perimeter of rectangle P=L + W + L + W The problem states: P=78 L=W + 3 Substitute the above values into the perimeter equation.

math
Generally, a fraction would be considered undefined if the denominator is 0. For the problem, what values of x would make the denominator 0?

algebra
p1 = -2,0 p2 = 0,1 slope = (1 - 0)/(0 - (-2) ) = 1/2 =0.5

math final tmrw!!!!!!!
(x + a)(x + a) =x^2 + 2ax + a^2 In the problem, 2ax=22x 2a=22 a=11 substituting back (x + 11)(x + 11) x^2 + 22x + 121

Math
The exponent is evaluated first. So, you would evaluate 4^x first, then multiply that by 3. If the expression had been written as: (3*4)^x, then you would multiply 3*4 first and raise that product to the x power.

Math question - plz correct
Glad to help!

Math question - plz correct
Actually, you would have to multiply them by 4 because they are squared. You have the right idea. For the legs use: b=2*450km=900km c=2*355km=710km This would then give you 800^2=900^2 + 710^2 - 2(900)(710)cos(A) Solve for A using the same method you did before.

Math question - plz correct
A quick look finds that you missed the fact that the time the airplanes are 800km apart is 2 hours not 1 hour. The legs should be 2*355km and 2*450km.

Algebra
A good way to be sure is to put the lines into the familiear y=mx+b form. The second equation is already there. If the value of m is the same, the lines are parallel.

Algebra
Since it says "factor completely", I think you are correct with D.

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