Monday

April 21, 2014

April 21, 2014

Total # Posts: 21,815

**math**

identify the sequence 1.6, .8, .4, .2 as arithmetic, geometric, or neither and why.

**math**

C(g) = 2.19g

**math**

a gas station charges $2.19 per gallon of gas. use function notation to describe the relationship between the total cost C(g) and the number of gallons purchased g.

**math**

looks like 8 11 14 17

**math**

find the 1st 4 numbers of the sequence 3 n + 5

**math**

625cm/2500cm = 1:4 so, what's 5000/4 ?

**Math**

since you give no information as to their directions, I will assume they are traveling in opposite directions. So, if the .1kg mass is moving in the + direction, we have 0.1*0.4 - 0.2*1.0 = (0.1+0.2)v v = -8/15

**science**

why do people have a hard time moving a large rock out of the road

**science**

what animal would have less momentum then a 52 kg cheetah running at 10 m/s.

**science**

what is the momentum of a 20kg scooter traveling at 5.o m/s.?

**math**

this is bogus. Maybe X,Y,Z are all disjoint. So, Z – (X U Y) = Z maybe Z⊆(XUY) so Z – (X U Y) = Ø Looks like you're on your own for this one.

**math**

well, duh: (2,-3)

**Math**

w(2w+4) = 400 w = √201 - 1

**linear algebra**

3/4 as big as or 25% smaller than

**Math**

assuming you mean a 1 ft cube, then it has 4^3 = 64 smaller cubes. The 8 corners have 3 faces yellow The 12 edges have 2 blocks each with 2 faces yellow, making 24 The 6 faces have a 2x2=4 set of cubes with 1 face yellow, or 24 That leaves the interior 2x2x2=8 cubes all green

**Math 10**

the graph is a parabola, with vertex at t=1 h(1) = 20 see a picture and analysis at http://www.wolframalpha.com/input/?i=-5t^2+%2B+10t+%2B+15

**Math**

x+y = 14 30x+60y = 660 6 @ 30" 8 @ 60"

**Algebra**

w=t+11 2w+t=64 w = 25 t = 14

**physics grade 10 icse**

v is the same forces in ration 1:2

**calculus**

Hmmm. If the population is p, then we have dp/dt = kp dp/p = k dt ln(p) = kt + c p = c e^kt Now we know that p triples in 14 days, so we can forgo using e, and just use 3 as our base: p(t) = Po * 3^(t/14) so, starting with 100, and gaining 15 per day and losing 23 each day, ma...

**calculus**

if the printed area has width and height x and y, then the total area is a = (x+8)(y+12) and xy=384 a = (x+8)(384/x + 12) = 12x + 3072/x + 480 that is minimum when da/dx = 0, so we need 12 - 3072/x^2 = 0 x = 16 so the poster is (16+8) by (24+6) or 24x30

**math**

a pyramid has a height of 5 inches and a surface area of 90 inches squared. A similar pyramid has a height of 10 inches what is it's surface area?

**Math**

n(n-1)/2

**Algebra**

x/(2x-5) - 5/(6x-15) 3x / 3(2x-5) - 5 / 3(2x-5) (3x-5) / 3(2x-5) or 1/2 + 5 / 6(2x-5)

**math**

I have 7 different pairs of jeans and want to take 2 with me on vacation. how many different ways can you pick 2 pairs of jeans to take on vacation. sorry for not proofing before

**math**

pairs of jeans and want to take 2 with you. how many different ways can you pick 2 pairs of jeans.

**Math**

Use partial fractions to see that you have -1/x^2 + 2/x + 3/(x+2) Now it's a piece of cake, right?

**math**

well, how many numbers are there? 10 how many are divisible by 2? 5

**math**

you have a spinner labeled 1 through 10. you spin once. what is p (divisimble by 2)

**Calculus**

y = xe^(-4x) y' = (1-4x)e^(-4x) y" = 8(2x-1)e^(-4x) since e^(-4x) > 0 for all x, y" < 0 when 2x-1 < 0. see the graph at http://www.wolframalpha.com/input/?i=+xe^%28-4x%29+for+0+%3C%3D+x+%3C%3D+1

**maths**

substitute y=7-2x and you have x^2 - x(7-2x) = 6 x^2 - 7x + 2x^2 - 6 = 0 3x^2 - 7x - 6 = 0 (3x+2)(x-3) = 0 x = 3 or -2/3 so, y = 1 or 25/3

**CALCULUS**

algebraically, since both functions are symmetric about the origin, the area is zero. geometrically, using symmetry, you have the area is 2∫[0,pi/9] (tan3x - 2sin3x) dx = 2/3 (2cos 3x - log cos 3x)[0,pi/9] = 2/3 (log2 - 1)

**CALCULUS PLEASE HELP**

seems pretty straightforward. We have ∫[0,10] 2300e^(.024t)-1450e^(.018t) dt = 10107.8 see http://www.wolframalpha.com/input/?i=%E2%88%AB[0%2C10]+2300e^%28.024t%29-1450e^%28.018t%29+dt

**CALCULUS**

If I read it correctly, you have y=4/x, y=16x, and y=x/16 for x>0 You need to break the area into two regions, because the two top curves intersect at x = 1/2 So the area is ∫[0,1/2] 16x - x/16 dx + ∫[1/2,8] 4/x - x/16 dx = (8x^2-x^2/32)[0,1/2] + (4logx-x^2/32)[...

**math**

7/10 * 6/9

**algebra**

(1+.09/12)^(12x) = 500000/25000 x = 33.411 years I figure you can calculate the required day

**algebra**

just solve for t in (1/2)^(t/5715) = 0.76 t/5715 = log(.76)/log(.5) t = 2262 makes sense, since 76% is about half way to 50%.

**math**

take a look here: http://www.wolframalpha.com/input/?i=plot+x%2B2y%3D-2%2C+-2x%2By%3D14+%2C+x%3D0%2C+y%3D0

**birzit**

find t with 5t^2 = 20 then use that t to find the distance d in d = 25t

**maths**

Since the formula says BAC% = ... I'd say just set it up as 0.1 = (5.14)(4*16*.04) / (.73)(12.5*14) - 0.015H H = 0.2 hours

**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

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