Wednesday

January 28, 2015

January 28, 2015

Total # Posts: 28,424

**Math help!!!**

First step: list the ordered pairs. (Mona,Kellie) ...
*November 20, 2014*

**Math**

You don't say whether these are courses from due North, or from the positive x-axis. I'll do the latter. the x- and y-components of the vectors are (450 cos65°, 450 sin65°) = (190.18,407.84) (35 cos20°, 35 sin20°) = (32.89, 11.97) Add them up to get (...
*November 20, 2014*

**english**

The current exchange rate is 1 yen = 0.0085 dollar So, a little less than 1 cent per yen. Or, a little more than 100 yen/$ 1/.0085 = 111.65
*November 20, 2014*

**English**

and you are correct.
*November 20, 2014*

**Pre Calculus**

P(0) = 160/(1+9) = 16 Just plug in t=6 for the population after 6 years. Note that as t->∞, e^-0.165t -> 0 So, the maximum possible population is 160 See http://www.wolframalpha.com/input/?i=160%2F+%281+%2B+9e^%28-0.165t%29%29+for+t+%3D+0..50
*November 20, 2014*

**Pre Calculus**

25*e^-5k = 18.4 So, k = ln(18.4/25)/-5 = 0.0613 So, now just solve for t in 25*e^-.0613t = 20.5
*November 20, 2014*

**Pre Calculus**

solve for m months in (1+.065/12)^m = 2
*November 20, 2014*

**Pre Calculus**

after t years, the population p is p = 127000 * 0.976^t Now just plug and chug
*November 20, 2014*

**algebra**

k = (h+j)+14 = x + x+4 + 14 = 2x+18
*November 20, 2014*

**Pre-Calculus**

The numbers are surely C:1 B:2 A:3
*November 20, 2014*

**math**

multiply or divide first, left to right. Then add or subtract, left to right. So, we have 5x5-5+5 25-5+5 20+5 25
*November 20, 2014*

**Math**

they are where y=0. If the product of two factors is zero, one of the factors must be zero. So, set them to zero and solve for x: x-6 = 0 means x = 6 and similarly for the other factor.
*November 20, 2014*

**Math**

(a) has three factors, so it will be a cubic, not a quadratic.
*November 20, 2014*

**Chemistry**

the volume has increased by a factor of 200, so the molarity has decreased by the same amount. 6.00/200 = 0.03
*November 20, 2014*

**math - I'm stumped**

So, now you know that d(t) = 5+b sin(ct) Now plug in the values you know: b sin(12c) = 0 b sin(1300c) = 2 b sin(1400c) = 3.46 we can see that 12c is a multiple of π. So, sin(1300c) = sin(1296c+4c) = sin(4c) sin(1400c) = sin(1392c+8c) = sin(8c) Hmmm. I'm stuck. 4c and ...
*November 20, 2014*

**Algebra**

yes, as you can easily verify with any of many online calculators...
*November 20, 2014*

**Algebra Help**

There is no easy analytic method. The best bet is a graphic or numeric method. You can see from http://www.wolframalpha.com/input/?i=solve+lnx+%3D+-4x that the solution is x = 0.3
*November 20, 2014*

**geometry**

if the sides are in the ratio of 3:4, the areas are in the ratio (3:4)^2 = 9:16
*November 20, 2014*

**Calculus Please check**

Looks good, except for the last one. It has no critical points, since Fx is never zero. Note that the critical points are where both Fx and Fy are zero.
*November 20, 2014*

**Math**

the circumference if the can is 2π. So, there are 10*36/2π labels per roll
*November 20, 2014*

**algebra**

http://www.wolframalpha.com/input/?i=y%3C-x-1%2C+y%3Ex%2B4&dataset=
*November 19, 2014*

**algebra2**

no idea. What's the connection between the BMW and the savings account?
*November 19, 2014*

**algebra2**

15000 * e^(30*0.0133)
*November 19, 2014*

**Math**

yep - it's there. Was there a question somewhere in there?
*November 19, 2014*

**Trig**

Draw a diagram. If the stations are labeled W and E, and the balloon is B, then angle WBE = 16° angle WEB = 106° So, the distance WB can be found using the law of sines: WB/sin106° = 161/sin16°
*November 19, 2014*

**math**

just do a little synthetic division. What do you get?
*November 19, 2014*

**Algebra**

Not quite (2^x)(2^x)(2^x)(2^x) = 2^(x+x+x+x) = 2^4x What you have is 2^x+2^x+2^x+2^x = 2^x(1+1+1+1) = 4*2^x = 2^2 * 2^x = 2^(x+2) So, now you have 2^(x+2) = 2^9 x+2 = 9 x = 7 128+128+128+128 = 512
*November 19, 2014*

**Algebra Two**

well, that would be (7x+4)(3x-9)
*November 19, 2014*

**algebra 1**

-4x-2y = -12 4x+8y = -24 add the two equations and you have 6y = -36 y = -6 now use that to get x
*November 19, 2014*

**Math**

First step: list the ordered pairs. (Mona,Kellie) ...
*November 19, 2014*

**Algebra**

solve for p in p(1+.12/2)^(2*7/2) = 45000
*November 19, 2014*

**Algebra 2**

x is x^1, so x*x^7 = x^(1+7) = x^8 the final answer is thus x^8/2
*November 19, 2014*

**math**

12/(12+6) = 12/18 is that at least 0.65?
*November 19, 2014*

**physics**

At the top of the toss, all the KE has been converted to PE, so 1/2 mv^2 = mgh or, v^2 = 2gh
*November 19, 2014*

**physics**

figure the distance each has traveled, and use the law of cosines to get the final separation. Start by drawing a diagram, so you know what's what.
*November 19, 2014*

**Algebra**

2000(1+.05)^18
*November 19, 2014*

**Algebra**

Assuming the coordinates are for the kite and the shadow, then the equation describing the line from the kite to the shadow is y = 4x Its slope is 4, so the slope of the string is -1/4. Its equation is y-12 = -1/4 (x-3) So, the x-intercept is (51,0) Thus, the distance is 51 ft
*November 19, 2014*

**MATH!!!**

b = 5a/11 c = 5b/11 d = 5c/11 what is the "agreed"? plug in your final result c+?+d=750 and then start substituting in to get a
*November 19, 2014*

**physics**

Ever heard of E=mc^2 ?
*November 19, 2014*

**math**

3/2 is more than 1 5/6 is just under 1 So, the only two that can cause trouble are 1/8 and 2/9 1/8 = 9/72 2/9 = 16/72 So, the order is clearly 1/8 2/9 5/6 3/2
*November 19, 2014*

**math**

area is proportional to the scale^2. So, 12cm^2 * (10^4)^2 = 12*10^8 cm^2 since 1m^2 = 10^4 cm^2, that means the area of the real lake is 12*10^4 m^2 = 12 ha
*November 19, 2014*

**Math**

#1 The first equation says y=6-4x. So, use that in the second equation and you have x-2(6-4x) = 15 Do #2 in like wise. Or, you can say that 2x = 10-y, so since 4x = 2(2x), 2(10-y)+2y = 5
*November 19, 2014*

**English**

Good idea. What do you have to say?
*November 19, 2014*

**math**

little kids
*November 18, 2014*

**math**

#1 We see that x = y-2, so 2(y-2)+5y = 9 Do the others in like wise.
*November 18, 2014*

**math**

You know you have at least 3 nickels, because only $5.75 can be made with just quarters. So, you have at most 47 quarters. 47 quarters = $11.75 plus 3 nickels = $11.90 That is $6.00 too much. Each quarter replaced by a nickel reduces the value by 20 cents. Since you have $6.00...
*November 18, 2014*

**3rd grade math**

all multiples of 2 are even every even row contains all evens every odd row contains multiples of 2 in the even columns. Similarly for the columns.
*November 18, 2014*

**trigometry**

Did you draw a diagram? If so, then it's easy to see that sinθ = 20/75
*November 18, 2014*

**Calculus**

yes, the product rule, and also the chain rule: y = (x)(e^-x^2) y' = (1)(e^-x^2) + (x)(e^-x^2)(-2x) = (1-2x^2)e^-x^2 If y = e^u, then y' = e^u u'
*November 18, 2014*

**Algebra 2**

recall that since i^2 = -1, 1/i = -i 1/(-1-i) * (-1+i)/(-1+i) = (-1+i)/2 1/(2i) = (1/2)(1/i) = (1/2)(-i) = -1/2 i
*November 18, 2014*

**CAL**

the tangent line has the same slope as the curve at the point of tangency. The slope at any x is y' = x^2-1 So, y'(1) = 0 Now you have a point and a slope, so the line is y + 2/3 = 0(x-1) or, y = -2/3 See the graphs at http://www.wolframalpha.com/input/?i=plot+y%3D+x^3...
*November 18, 2014*

**Algebra**

p = kv^2 so, if v is replaced by 2v, then p becomes k(2v)^2 = k*4v^2 = 4kv^2 = 4p So, p grows by a factor of 4. Makes sense, since p grows as v^2.
*November 18, 2014*

**algebra 1**

not quite ∛-64 = -4 (8 is √64) also, you need to divide both exponents by 3. 8=3*2+2 and 5=3+2 so, the answer is -4x^2y ∛(x^2y^2)
*November 18, 2014*

**algebra 1**

it's pretty, but it's not the answer ...
*November 18, 2014*

**Math**

eh? x <= 49 is "not more than" So, I'd pick (1)and(3)
*November 18, 2014*

**math**

multiply top and bottom by 2i: (-5+i)(2i)/-4 = ?
*November 18, 2014*

**math**

how about x^2+5x-3 = x+2 x^2+4x-5 = 0 Now it's a cinch, right?
*November 18, 2014*

**6G Math (pls check my answer)**

both are correct
*November 18, 2014*

**math**

(12.3x10^11)(1.5x10^-12) = (12.3*1.5)x10^(11-12) = ?
*November 18, 2014*

**trig**

recall your basic trig functions: sin x = 3.5/12
*November 18, 2014*

**math**

You could clear fractions, but that would produce quadratics in x and y. An easier method might be to identify new functions, u and v: u = 1/(2x-y) v = 1/(3y-x) Then the two equations become 6u + 7v = 7 4u + 14v = 6 Now if you double the first equation and subtract, you wind ...
*November 18, 2014*

**Calculus**

At t=0, let's say that Frodo was at (1,0), 1 km east of Aragorn, who was at (0,0) At time t hours later, the two parties were at (1+4t,0) and (0,-12t) So, the distance d(t), between the parties is given by d^2 = (1+4t)^2 + (-12t)^2 d^2 = 160t^2 + 8t + 1 At t=1, d=13 Now, ...
*November 18, 2014*

**Math**

Take a look at how your other problem was solved. 18/3 = x/2 or 18/x = 3/2
*November 18, 2014*

**GEOMETRY**

just note that S is the same distance from M (the midpoint) as T is. So, for the x-coordinate, Mx-Sx = Tx-Mx 5-Sx = 10-5 5-Sx = 5 Sx = 0 Makes sense. We went from 10 to 5 to get from T to M. So, we have to drop another 5 to get to S: result is 0. Now do the same for the y-...
*November 18, 2014*

**Math**

for every 5 NA butterflies, there are 3 SA. 30/5 = 6, so there are 6*3=18 SA butterflies.
*November 17, 2014*

**Advanced math**

Is this a trick question? Fourier series use sine and cosine to approximate other kinds of functions. You already have sine functions.
*November 17, 2014*

**Maths**

yes, use cos to find how far away the wires are anchored. Then use that distance and cos again to find the smaller angle. Then use sin to find the heights on the tower. Or, equivalently, use the Pythagorean Theorem to find the heights, since you have the base and tbhe ...
*November 17, 2014*

**math**

Let's say there are x students in total. Clearly 3/8 of the students are girls. So, if there are n groups of girls, we have n(x/6) = (3/8)x 4nx = 9x 4n = 9 I don't see any way to divide the girls evenly. Did I miss something?
*November 17, 2014*

**math**

we have s = kv^2 That is, s/v^2 is constant. So, now we know that 170/50^2 = x/55^2 Note that we don't really need to know the value of k, just that it is constant.
*November 17, 2014*

**plane and spherical trigometry**

If the nearer object is at distance x, and the two are distance d apart, then we have 57/x = tan27° 57/(x+d) = tan40°5' Now just solve each euation for x, and set the two equal: 57/tan27° = 57/tan40°5' - d Now just find d.
*November 17, 2014*

**algebra worksheet help please**

A correct B correct, except that I think you mean 0.966^x C yes: C = 1500-5x
*November 17, 2014*

**Math**

generally the vertical axis represents the function of the value on the horizontal axis. I suspect there is more you want to ask. Remember that google is your friend.
*November 17, 2014*

**math (stats)**

60 = 50+10 so, it is 10/8 = 1.25 above the mean Check you Z table to find P(Z<1.25)
*November 17, 2014*

**Reading**

Adhered, scan or transferred I guess the for helping
*November 17, 2014*

**Reading**

On my reading worsheet we are supposed to find antonyms of words and one word was analyze and the options to match antonyms were not going in to any word Like on google it gives me synthesize or combine but neither word is on my worksheet please help
*November 17, 2014*

**math**

If the digits are a,b,c then the value of the original 3-digit number is 100a+10b+c So, now we know that 100a+10b+c = 11(10a+c) b-a = 1 we want to find c 100a + 10(a+1) + c = 110a+11c 100a+10a+10+c = 110a+11c 10+c = 11c c = 1
*November 17, 2014*

**Calculus - PLEASE HELP!!**

⌊x⌋ has no maxima and minima. It is a piecewise linear function, and each piece is a horizontal segment of length 1. Since a critical point is where the derivative is zero or undefined, then that would be every real number, since at the integers, ⌊x⌋ is...
*November 17, 2014*

**trig**

the angle of depression from the top of the tower is the same as the angle of elevation from the ground to the top. So, if the nearer goat is at distance x, and the distance between the goats is d, then tan 17° = 75/x tan 10° = 75/(x+d) So, if we solve for x in both ...
*November 17, 2014*

**Math**

since y = 5-2x, x^2 + (5-2x)^2 = 50 x^2 + 25 - 20x + 4x^2 = 50 5x^2 - 20x - 25 = 0 x^2 - 4x - 5 = 0 (x-5)(x+1) = 0 (x,y) = (5,-5) or (-1,7)
*November 17, 2014*

**Derivatives**

if u = 5x^2, then g(u) = tan u dg/du = sec^2(u) dg/dx = dg/du * du/dx = 10x sec^2(5x^2)
*November 17, 2014*

**Calculus Can you help**

g(1) = 2 f'(2) = 2π h'(1) = f'(2)*g'(1) = -6π you are correct
*November 17, 2014*

**CAL**

I is neither continuous nor differentiable f(x) does not exist for x<1, so there is no limit from the left. Taking just the limit on the right, y' does not exist at x=1. II is not continuous, so cannot be differentiable y(1) = 1 lim x->1+ = 2 III is continuous, bit ...
*November 17, 2014*

**college algebra**

well, clearly the population, starting from an initial value of P, is p(t) = P(0.9952^t) after t years. So, p(40)/P = 0.9952^40 = 0.8249 That makes a decrease of 17.51% I think you can now refute the argument about zero population.
*November 17, 2014*

**math**

Consider the point on shore that is closest to the station. I can't tell from your explanation, but I will say that x is the distance from there to where the line comes ashore. That means 8-x is the rest of the way to the factory. So, using the Pythagorean Theorem, the ...
*November 16, 2014*

**Thank Jiskha tutors**

I can't speak for us all, but I had a lot of fun helping my kids through math and science when they were in high school. I hang out here because I have fun working the problems, and have even picked up a few useful tips from the other tutors. And, I am constantly amazed at...
*November 16, 2014*

**math**

c = 2d (d-29) = 2(c-166) Now just solve for c and d
*November 16, 2014*

**Physics question**

some problems pop up all the time. A boat crossing a river has to account for the current a plane has to compensate for wind speed Two ships at sea use radar to detect each other. Any time there are moving items, vectors are used to describe their location or speed.
*November 16, 2014*

**arithmetic**

divide both sides by 15
*November 16, 2014*

**physics**

all the KE is converted to PE. So, 1/2 mv^2 = mgh So, solve for h.
*November 16, 2014*

**Physics**

Find the time to hit using 4.9t^2 = 45.9 Plug that t into get Vx Vx = 121/t Vx does not change Vy = -9.8t
*November 16, 2014*

**math**

why the fourth factor? I'd say 1/27 What happens on the 2nd question does not matter.
*November 16, 2014*

**Math**

The diagram at http://mathworld.wolfram.com/images/eps-gif/EqTriangleInscribeCirc_1001.gif should help.
*November 16, 2014*

**Pre Albergra**

Your approximation to pi is lousy...
*November 16, 2014*

**Pre Albergra**

If they are similar with ratio r, then TP = r*(EA)
*November 16, 2014*

**Math (calculus)**

under power, a(t) = 8 v(t) = 8t h(t) = 4t^2 So, v(10) = 80 h(10) = 400 Now, in ballistic path, only gravity affects the motion, so for t>10, h(t) = 400 + 80(t-10) - 9.8(t-10)^2 = -1380 + 276t - 9.8t^2 Now you can find the vertex, the roots, etc.
*November 16, 2014*

**algebra**

if you can graph one line, surely you can graph two. You can see the two lines at http://www.wolframalpha.com/input/?i=plot+y+%3D+-1%2F3+x+%2B+2%2C+y%3Dx-5+for+x+%3D+-5+to+10 Just pick the blue line left of x=0 and the purple line to the right.
*November 16, 2014*

**Calculus I (PLEASE HELP!)**

so, what is confusing you? Newton's method says that, if you have an estimate a root of f(x)=0, you can get a better estimate by using the formula f(x) -> f(x) - f(x)/f'(x) You have the function f(x) = x^2-5, so that f(√5) = 0. f'(x) = 2x. So, you start ...
*November 16, 2014*

**MATH**

It would help if you showed your work. How do you get 5? x is °C f(x) is ml, so the rate of change of ml/°C is just Δf/Δx = 5/5 = 1 For problems like this, you must read the question carefully to see just what they are asking. You gave the quantity of change...
*November 16, 2014*

**calc**

no idea what the regions are. But if f(x) = F'(x), then the areas are x^3+2x+F(x)[2,4] = (64+8+F(4))-(8+4+F(2)) Presumably you have some way of finding F(x)
*November 16, 2014*

**1210 Math**

Assuming you mean f(x) = -x^2 + 2x + 2 you want to find x where f(x) = 0. That is where it hits the ground. So, just solve the quadratic as usual.
*November 16, 2014*

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