Wednesday

April 23, 2014

April 23, 2014

Total # Posts: 21,876

**maths**

you have the formula, and you have the numbers. What's the trouble? (aside from converting stones to lbs)

**maths**

g = 32 ft/s^2 ya just gotta know some things

**maths**

solve for t in 16t^2 = 5 then plug that t into the distance d = 600t

**math**

z^2 = -2j = 2cis(3pi/2) z = √2 cis(3pi/4) = √2 (-1/√2 + 1/√2 j) = -1+j

**math**

1.1c - 150 = 0.6c c = 300

**word problem**

just solve 34.1 lnx + 117.7 = 250 34.1 lnx = 132.3 lnx = 3.88 x = 48.4 so, we're looking at 2048

**Algebra**

Hmm. I read it as x(x-7) = 8 Oddly enough, the answer is the same!

**finance**

(1+r)^4 = 73800/52500 = 1.4057 1+r = 1.0888 r = 8.9%

**Finance**

(1500(1+.04/4)^(4*5) + 500)(1+.05/4)^(4*5) = 2987.51 2987.51 - (1500+500) = 987.51 330.29 on the 1st deposit 657.22 on the 2nd deposit

**math**

3/5 x + (1/3)(2/5)x = 110 x = 150 so, he had $40 left.

**logarithim**

remember that 9^x = (3^2)^x = 3^(2x) so, setting everything to base 3, you have 3^(x-2) = 3^(2(x+4)) now take logs to base 3 on both sides (meaning: if the numbers are equal, then the powers are equal), to get x-2 = 2(x+4) x = -10

**algebra**

{f,o,d}

**algebra**

yes. Then since the logs are equal, so are the numbers, and you have (x+3)/(x-5) = 7 x = 19/3

**algebra**

3ln(4x) = 17 ln(4x) = 17/3 4x = e^(17/3) x = (1/4) e^(17/3)

**algebra**

3x+2 = 7^5 x = (7^5-2)/3 = 16805/3

**algebra Word problem**

e^15r = 3 15r = ln3 r = ln3/15 = 7.3%

**algebra**

since you probably don't have a log base 5 button on your calculator, you need to change base. log5379 = log379 / log5 and on the right, you can use any base you want: e or 10

**math**

(3.835/100.00)v = 283.79 v = 7400.00 wow - cheap house!

**Math HELP**

11 cm = .11 m, so now it is 1.6 + .11 = 1.71 m high don't know why you were messing with times tables. They gave you the old height and told you how much it grew. Just add the two numbers!

**Math**

one week ago was 7 days ago.

**algebra**

just use the distance formula, which I'm sure you know. The length of the line segment is just the distance between the points: √((0-3)^2+(-6-0)^2) = √(3^2+6^2) = √45 = 3√5

**Physics**

mv = 7.84*10^7 acceleration from the force is a = F/m = -1.29*10^6/m so, v after force is 7.84*10^7/m - (1.29*10^6/m)(9.65) = 6.6*10^7/m so the final momentum is 6.6*10^7 kg-m/s sorry about using m for mass as well as meters.

**Stats.**

Wow - you must give up easy. For #a, click the Between button and enter the two values. Then click recalculate. It will show the relevant area and its probability: .0955 If you know the area and want the bounds, then click on the Value from an Area button.

**Stats.**

a good place for playing around with Z table stuff is http://davidmlane.com/hyperstat/z_table.html

**algebra**

no reason to estimate, since the quadratic formula provides their exact values. x = (3±√65)/4 since √65 is very close to 8, a good approximation would be x = 11/4 or -5/4

**trig**

just use your calculator to find the angle with the given property. Then solve for x. For example, tan 58.7° = 1.6443 Since the period of tan(x) is 180°, you have to find x where 90-2x = 58.7: 2x = 31.3, so x = 16 2x = 211, so x = 106 also, continuing on, x = 196,286 D...

**trig**

cos(x) assumes all values between -1 and 1. Each of those values appears twice in a period of the curve. Since you want a unique value, x = 0 so cos(x) = 1 or x = 180, so cos(x) = -1 for any other value where cos(x) = k, cos(360-x) is also equal to k. Look at the graph and you...

**trig**

either 1 or -1 is attained only once on the given domain.

**math**

3/8 + 5/8 = 1 so, you still have 5/8 to go. and, believe it or not, "further" and "farther" are not interchangeable.

**English grammar**

while and unless can have opposite meanings I will stay inside while it's raining. I will go outside unless it's raining. Of course, there are other meanings as well, as in While I'd love to help you, I can't, unless you tell me what's wrong.

**MATHS - HCF**

LCM(25,45,60) = 900 So, 920 will do the trick. 70 = 16 + 3*18 = 10 + 5*12 = 22 + 2*24

**isd muscat**

1/16 is left after 4 half-lives (1/2^4) so, 2 hours is 4 half-lives. ...

**math - typo?**

I think that the "d" is a typo.

**Calculus**

the discontinuity is non-removable. There's no way to define f(x) there so that the two limits are the same and equal f(x).

**math**

just list the numbers: 140 120 100 80 60 40 20 0 120 110 100 90 80 70 60 50 40 30 20 10 0 So, how many numbers are in both lists?

**science**

p = mv = 20kg * 5 m/s = 100 kg-m/s

**science**

what is the momentum of a 20.0 kg scooter traveling at 5.00 m/s?

**Calculus**

just apply the definition. What's the problem? f(x) = 1/x f(a) = 1/a f(x)-f(a) = (a-x)/(ax) Now divide that by x-a and you have -1/(ax) the limit as x->a is -1/x^2 So, fix your typo and adjust the evaluation. (1,1/5) is not on the curve for 1/x.

**math**

n! = n(n-1)! 1! = 1 so, 1 = 1*0!

**Math**

the formula is a = 2pi*r(r+h) 2*pi*8(8+8) = 803.8 If you just want the lateral area, or the area of the two ends, then you get half that. So, reread the question and make sure you are both on the same page for how much of the area you want to consider.

**math**

48 is 3/4 of 64 cents so, what's 3/4 of 16 inches?

**math**

18 / (3/8) = 18 * 8/3 = ?

**algebra**

x^2+10x-24 = 0 (x+12)(x-2) = 0 Looks like D to me.

**math**

n(t) = 15000*3^(t/8)

**Math**

the integral of the u stuff is just u + log(u) - 1/u so the whole thing is just 72/7 + 5log(7/5)

**Math**

that would be f(2)-f(0) = 3.68 - 2.64

**Math**

R(x) = ∫R'(x) dx = -0.05x^2 + 40x Now just plug in your x values.

**5th Grade Math**

c = 5d d = m+187 c = 15250 (change km to meters) you want m, so start substituting m = d - 187 = c/5 - 187 = 350 - 187 = 163

**Math**

∫√(11x)(√x + √11) dx = ∫√11 x + 11√x dx now it's just straight powers of x, so we have ∫[0,1] √11 x + 11√x dx = √11 x^2/2 + 11(2/3) x^(3/2) [0,1] = 22/3 + √11/2

**functions (easy explanation)**

well, you surely know that 5^x > 0 for positive x. It grows from 5,25,125,625,... getting ever larger Now, negative exponents are reciprocals. So for negative x, you just have 1/5, 1/25, 1/125,... No negative values for y, just smaller and smaller.

**Math**

nope. All you know is that bh/2 = 22 Pick any value for b, and you can figure h, but you can't pin them both down.

**Math**

1-6 are ok #7 is no. You can divide 22 up into a product in many different ways.

**math**

4*8*L = 256 L = 256/32 = 8

**Calculus**

you know the slope of the tangent for y = f(x) at any point is m = dy/dx So, for y = x^2-2x, the slope at any x is y'(x) = 2x - 2 So, at (0,0), mm = -2 If you want to estimate the slope, pick two x values close to zero and find the slope between those two points on the cur...

**Math**

I'd say use the average of the averages. But, it depends on what you want. Not sure that a "team average" has any real meaning. Depends on how you define it. If you average the averages, it decreases the importance of hitters who have been up many times, as their...

**math**

784 = 28*28 All we know about the parallelogram is that its base=28 and its height=28 The long sides can be anything greater than 28, depending on how flat the parallelogram is.

**math**

(10/2) m^(2-5) = 5/m^3

**math**

1 1/2 inches is 3 times 1/2 inch so, what's 3 times 5 yards?

**math**

consider the data points 1 10 20 1 2 3 4 10 10 10 17 18 19 20 same center, same max Yiu can surely come up with many variations where the same conditions hold.

**Math**

I get A why not use actual math symbols instead of words? 3x^5 / 15x

**trig**

cosA = 3/5 sinB = 15/17 tanA = 4/3 tanB = 15/8 tan(A-B) = (tanA-tanB)/(1+tanAtanB) = (4/3 - 15/8)/(1+(4/3)(15/8)) = (-13/24)/(7/2) = -13/84

**Math**

r^2s^5t^4 / r^2s^2t^5 = s^3/t

**Math**

each flavor can be chosen or not, making 2^7=128 possible combinations of flavors. One of those is none at all, so if you discard that, it leaves 127.

**math**

x-3 >= 0

**math**

subtract y from both sides and you have 3.9 > 0 which is true for any value of y you choose.

**Calculus**

The volume is v(t) = 40(400-40t+t^2) the rate of change is the derivative, so v'(t) = 40(-40+2t) v'(10) = 40(-40+20) = -800 2a Since your solution used 5/3, I will assume a typo in the problem. if you meant (5/3) + x, the slope is always 1 if you meant 5/(3+x) then the...

**trig**

540 @ 50° = <413.66,347.11> wind is <0,-27> add them up to get <413.66,320.11> which is 523 @ 37.7°

**Permutations**

as you know by now, after all the problems you have posted, n things can be permuted in n! ways. If there are m duplicates, divide by m! so, for PROPOSITION, since there are 11 letters 2 P's 3 O's 2 I's there are 11!/(2!3!2!) distinguishable permutations of the let...

**Circle geometry**

draw a diameter through the center of the chord. draw a radius to the end of the chord. now, the distance d from the chord to the center can be found using d^2 + 25^2 = 35^2

**Math**

I assume you want values of x which solve the equation. Well, you know the rational roots will be of the form 1,2,5,10 or 1/5,2/5 A little synthetic division shows that x+1 divides twice, so you have (x+1)(x+1)(5x^2-51x+10) Now you can easily see that it is (x+1)(x+1)(x-10)(5x...

**algbra**

x is in {2,4,6,8,10} U {3,6,9} I assume you can find that union, no?

**Geometry**

cube, brick, sphere, cylinder, cone, what? whatever the shape, I assume you have a volume formula. Plug in your numbers and show us whatcha got, so we can check it.

**Math**

(cosx + 1)^2 = 0 cosx = -1 that should help, no?

**Algebra**

row: (17.2+10.4)/2 = 13.8 water: 13.8-10.4 = 3.4

**Math**

e^jπ/4 = cos(π/4) + j sin(π/4) = 1/√2 + 1/√2 j Assuming j^2 = -1, you have -e + e^1.2 j

**maths**

If P+Q makes a 45° angle with both P and Q, then P must be perpendicular to Q. So, |P+Q| = √(|P|^2 + |Q|^2)

**Calculus**

#1 yes. the speed has a constant rate of increase #2 v(t) = t(2t^2-t-15) = t(2t+5)(t-3) You are correct, that b and c are both solutions. But doesn't negative time present a problem? I think that in the real world I'd have to go with just (c).

**math**

y = -(x^2+4x-5) y = -(x+5)(x-1) Now, if a product of factors is zero, any of the factors can be zero. So, which values of x make each of the factors zero?

**Algebra**

(x+4)(x-4) / (2x-1)(x-4) * 4(x+1) / 2(x+3)(x+4) the x-4 and x+4 cancel, and we are left with 2(x+1) / (2x-1)(x+3) where are all the x's in your answer? next time you post this problem (again), why not show your work, so we can see what's giving you trouble?

**Math**

recall that ∫ e^u du = e^u ∫e^(4x) dx let u = 4x, so du = 4 dx. That means that you have ∫e^(4x) (1/4)(4x dx) = ∫ 1/4 e^u du = 1/4 e^u = 1/4 (e^4x) similarly, for any constant a, ∫e^(ax) dx = 1/a e^(ax) and as always, don't forget the +C !

**Algebra**

since the bottom is square, you will be using a square piece of cardboard. So, if the uncut piece is of side x. after the cut, you will have volume v = (x-6)^2 * 3 Now, you want v=42, so solve 3(x-6)^2 = 42 (x-6)^2 = 14 x = 6+√14 so, after cutting and folding, the volume...

**math**

what, you can't use a calculator to find that A: 85*.045 = $3.825 per tire sales tax 3.825 * 580 = $2218.50 total sales tax ?? now do the same for B

**math**

A 85*.045 per tire multiply that by 580 tires for total B .15*50 per tire *580 for total C add $85 and per-tire taxes for total price per tire. *580 for total price.

**Algebra**

x^2+8x+15 = (x+3)(x+5) x^2-16 = (x+4)(x-4) so, what you have is (x+3)(x+5) / (x-4) * (x-4)(x+4) / 2(x+3) Now you see that x+3 and x-4 cancel out, leaving (x+5)(x-4)/2

**algebra**

using the value of the coins (in cents), we have 5n+10d = 760 1n+10d = 680 subtract and you have 4n = 80 n = 20 so, d = 66 Or, you can notice that he loses 4 cents for each nickel-penny swap. Since he lost 80 cents, that'd be 20 nickels changed to pennies.

**Math Help? Check my answers.**

looks good to me. except the spinner sections are numbered 1-10, not 0-10.

**Algebra**

2x^2-9x+4 = (2x-1)(x-4) 2x^2+14x+24 = 2(x+4)(x+3) so, what you have is (x-4)(x+4) / (2x-1)(x-4) * 4(x+1) / 2(x+4)(x+3) the x+4 and x-4 cancel, so we have 2(x+1) / (2x-1)(x+3)

**Math**

9! ways if all different but the 4 red flags can be arranged in 4! ways, but they are identical. Similarly for the other colors, so the distinguishable arrangements are 9!/(4!2!3!)

**MATH VERY URRRGENT!!!!!!!!!!!!!**

I think bobpursley's answer is correct, as to the type of probability illustrated. No numbers can be calculated without knowing what it is you are trying to draw. Having said that, I can't think of any target draws that would amount to 5/52. That is just the fraction o...

**MATH VERY INCOMPLETE!!!!!!!!!!**

Hmmph

**Math**

If you read carefully, I think you will find I did. 3 ways to choose the driver, 5! ways to arrange the riders.

**Math**

If you mean that the 6-person team must contain 3 drivers, then the driver can be selected in 3 different ways The remaining 5 riders can be arranged in P(5) = 5! ways If I have misread the problem, please clarify.

**Calculus**

or, u = 1-x^4 du = -4x^3 du so ∫(2x^3/√(1-x^4))dx = -1/2 ∫1/√u du = (-1/2)(2√u) = -√(1-x^4) Extra credit: Can you find the error in bobpursley's solution?

**math**

Looks like C to me can't mix x's and y's x^2*x^3 = x*x * x*x*x = x^5 but x^2 * y^3 = x*x * y*y*y

**Math**

Assuming you mean matrices and not determinants, take a look at http://www.wolframalpha.com/input/?i={{9%2C4}%2C{2%2C1}}+*+{{-9%2C-6}%2C{-1%2C-8}} The result is not one of your answers, so there's a typo somewhere. You can easily adjust the numbers on that web page, till t...

**Calculus**

I assume you meant fired straight up in the air. In that case, at time t seconds, the rocket has gone 2t miles. So, the distance D is found, as you showed, by D^2 = 9+y^2 = 9+4t^2 when the rocket is 4 miles up, t=2, and we have a 3-4-5 triangle, so D=5. 2D dD/dt = 8t when t=2,...

**Algebra 9**

2x^2-9x+4 = (2x-1)(x-4) 2x^2+14x+24 = 2(x+4)(x+3) so, what you have is x^2 / (2x-1)(x-4) * 4(x+1) / 2(x+4)(x+3) hm. no factors cancel but the 2's, so we wind up with 2x^2(x+1) / (2x-1)(x-4)(x+4)(x+3) = (2x^3 + 2x^2)/(2x^4+5x^3-35x^2-80x+48) Not very simple.

**Calculus**

your value x=2 is correct. a) yes, but v(25) represents the amount of fluid remaining after 25 minutes. It just happens also to be true that at that time the tank is empty. b) v(0) = 875 v(15) = 350 volume changed by -525 in 15 minutes, for an average rate of change of -525L/1...

**Math**

if the amounts are x,y,z for 6,7,8% respectively (in thousands), then we have x+y+z = 1200 z = x+y .06x + .07y + .08z = 88 x,y,z = 200,400,600

**Calculus Help Please!!! Urgent!!!**

-6x/y^5 is not the answer 3x^2 - 3y^2 y' = 0 now use the quotient rule: y" = (2xy^2 - 2x^2y y')/y^4 = 2x(y-xy')/y^3 = 2x(y-x(x^2/y^2))/y^3 = 2x(y^3-x^3)/y^5 or, use implicit differentiation twice: x^3-y^3 = 3 3x^2 - 3y^2 y' = 0 6x - 6y(y')^2 - 3y^2y&qu...

Pages: <<Prev | 1 | 2 | 3 | **4** | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>