Saturday

December 3, 2016
Total # Posts: 46,781

**maths - incomplete**

Not known, since (a) you did not say how many pictures there are (b) you did not say how many pictures are on a page (that has pictures) Try reading what you write before posting.

*November 7, 2016*

**Math**

can't be done 62% = 62/100 = 0.62 Not a whole number

*November 7, 2016*

**Chemistry**

Can you check my answers? Thanks!!!! What would happen to the volume-to-temperature ratio if: 1. One student failed to replenish the boiling water in the boiling-water bath as the flask was being heated. At the end of the 6 min of heating, the boiling water in the bath was ...

*November 7, 2016*

**Calculas-Differentiation**

you know that f'(2) = 0 2ax+b = 0 at (2,8) 4a+b = 0 4a+2b = 8 So, b=8 a = -2 y = -2x^2 + 8x see http://www.wolframalpha.com/input/?i=-2x%5E2+%2B+8x or, without calculus, you know that -b/2a = 2 since the vertex is there. so b = -4a y(2) = 8, so 4a + (-4a)(2) = 8 a = -2 so ...

*November 7, 2016*

**Algebra**

20% less, or 580*.80

*November 7, 2016*

**maths**

You keep posting this same stupid problem without enough description to pin it down. AB can be almost any length, depending on the shape of the figure. If the rectangle is ABCD, and the triangle has base CD and vertex E, then still all we know is that AB + 2*AD + 2*DE = 46 Of ...

*November 7, 2016*

**Geometry**

do you mean the two sides opposite each of the angles U and V? Normally a side opposite an angle (such as X) is labeled with the lower-case letter of the angle (x) , or the letters of the two vertices at the ends of the side. That would be sides u (VW) and v (UW)

*November 7, 2016*

**business math**

well, the amount of interest per day was 278/280 So, the percent interest per day was (278/280)/3800 = .0002613 = 0.02613% Now multiply that by how many days in a year ...

*November 7, 2016*

**arithmetic**

hmmm. what is the difference between 7 and 12? How did you get it? Do the same for these two numbers.

*November 7, 2016*

**Maths**

just list 'em for MSQ and then replace each letter with the corresponding one from UVW.

*November 7, 2016*

**dynmic**

what step by step? The same equation (h = vt - g/2 t^2) applies to both balls, so just set them equal: 30t-4.9t^2 = 50(t-3) - 4.9(t-3)^2 http://www.wolframalpha.com/input/?i=30t-4.9t%5E2+%3D+50(t-3)+-+4.9(t-3)%5E2

*November 6, 2016*

**Math**

LB: (360-7)/2 NO: (25-8)/2 Even without doing the actual math, just seeing that much of LB is quite high should make things clear. Now, neither of those averages is -2, but surely NO has a better chance of being near that. What that means is that while the mean of high and low...

*November 6, 2016*

**Math**

Sometimes it helps to use the intercept form of a line. 5x - 12y = 60 x/12 + y/-5 = 1 The intercepts are 12 and -5, you you have a 5-12-13 right triangle.

*November 6, 2016*

**Math**

It depreciated to 1/2 its value in 6 years. (1/2)^(1/6) = 0.89089 So, the depreciation rate is .1091 = 10.91% per year

*November 6, 2016*

**Calculus**

Wll, there is much unsaid here, but if we assume the pyramid has a square base of side length x, and height y, then V = 1/3 x^2 y = 2.2 y = 6.6/x^2 Now, the area of tent is x^2 for the floor 2x?(x^2+4y^2) for the sides So, you want to minimize the cost c = x^2 + 1.4*2x?(x^2+4y...

*November 6, 2016*

**statistics**

since the variable of interest is distance, it is continuous. Unless you are measuring the number of shots, which is discrete, but might be involved in a different sampling scheme...

*November 6, 2016*

**math**

h/(82*7*60) = sin 13°

*November 6, 2016*

**maths**

rectangles and triangles come in many shapes. You need to pin down some of the properties a little more exactly. Is the base of the triangle the same as one of the sides of the rectangle? Anyway, label the sides of your figure, and add them up. They must sum to 46. Can't ...

*November 6, 2016*

**Math**

p=3s s=j+4 p+20 = 2(j+20) Now just solve for p.

*November 6, 2016*

**Trigonometry**

If we label things as T: town P: plane A: airport Then in triangle TPA, using the law of cosines, 29^2 = 34^2+48^2 - 2*34*48*cosP P = 36.6° Now you can figure out the heading. (the same as the bearing of A from P)

*November 6, 2016*

**science**

electron clouds, rather than actual orbits.

*November 6, 2016*

**math algebra**

x at 3.5%, so the rest (3000-x) at 2.5% Now just add up the interest: .035x + .025(3000-x) = 190

*November 6, 2016*

**Calc 1**

I assume that you mean C(m) = (-.41m^2 + 6.7m - 44)/.7m As you recall from Algebra I, that is C(m) = (1/.7)(-.41m + 6.7 - 44/m) so, C'(m) = (1/.7) (-.41 + 44/m^2) = (1/.7)(44-.41m^2)/m^2 Since the denominator is always positive, C'(m)=0 when 44-.41m^2 = 0 m^2 = 44/.41 ...

*November 6, 2016*

**Calc 1**

no. e^(-3x) is never zero, so where is (1-3x)=0? x = 1/3 so, a = (1/3)e^(-3*1/3) = 1/(3e) don't forget your Algebra I now that you're in Calculus!

*November 6, 2016*

**Calc 1**

a = xy = xe^(-3x) da/dx = (1-3x)e^(-3x) so, where is da/dx = 0?

*November 6, 2016*

**College Alg**

40000(1+.08)^5 Good luck with that!

*November 6, 2016*

**College Alg**

P(1+.09/4)^(4*18) = 41000

*November 6, 2016*

**Algrebra readiness**

Not so. Think about your answer. 9+12=21 Those cannot be the sides of a triangle. The 9 and 12 sides would have to lie completely flat on top of the 21 side. The third side must be less than 9+12. In fact, if the 3rd sides is x, 12-9 < x < 12+9

*November 6, 2016*

**PreCalc Oops**

oops - that's a+4d=6 But I'm sure you caught that...

*November 6, 2016*

**PreCalc**

just crank it out using the formulas you already know: a+5d = 6 12/2 (2a+11d) = 45

*November 6, 2016*

**Calculus**

d^2s/dt^2 = -4cos(2t)+sec^3(t)+sec(t)tan^2(t) now just plug and chug.

*November 6, 2016*

**Algebra readiness**

?25 + -9 = 5-9 = -14 integer

*November 6, 2016*

**algebra**

I thought it was 13/84, but that does not work. However, 1/6 + 1/7 = 13/42

*November 6, 2016*

**Maths**

Using discs (washers), they stack up with thickness dy or dx, as needed. (a) v = ?[0,2] ?(R^2-r^2) dy where R=4 and r=x=y^2 = ?[0,2] ?(16-y^4) dy = 128?/5 (b) v = ?[0,4] ?(R^2-r^2) dx where R=2 and r=2-y=2-?x v = ?[0,4] ?(4-(2-?x)^2) dx = 40?/3 Or, you can use nested cylinders...

*November 6, 2016*

**Math, Precalc**

can't see your diagram, but consider the vectors representing the diagonals. If it's a unit cube, they might be joining (0,0,0) and (1,1,1) = <1,1,1> (1,1,0) and (0,0,1) = <-1,-1,1> (1,0,0) and (0,1,1) = <-1,1,1> ... Now just take the dot product of ...

*November 6, 2016*

**Calculus**

Actually, since f(x)=0 at all those points, we can use Rolle's Theorem, which is just a special case of the MVT were f(a) = f(b) on the interval [a,b]. Both theorems state that f'(c) exists with c in (a,b) such that the tangent is horizontal. That is, f'(c)=0, ...

*November 6, 2016*

**Math-Trigo**

Just draw your 5-12-13 triangle in standard position cot(90-A) = tan(A) = y/x = -12/5

*November 6, 2016*

**physic**

if 30°, then just find t when the height is zero: 30*sin30° t - 4.9t^2 = 0

*November 6, 2016*

**math**

Oops. adding the equations eliminates y. 7x = 28 ...

*November 6, 2016*

**math**

You meant: I can't; help me. 5x-2y = 14 2x+2y = 14 ------------- add the two equations 4y = 28 I expect that you can handle it from here, eh?

*November 6, 2016*

**Math**

6+2x=24

*November 6, 2016*

**math**

recall that a regular hexagon has sides equal to the circle's radius.

*November 6, 2016*

**calculus - PS**

#1 is not quite so amazing if you recognize that if a = tan(u) x = tan(v) y = arctan(tan(u+v)) = u+v y' = v' ...

*November 6, 2016*

**calculus**

recall that if y = arctan(u) y' = 1/(1+u^2) u' y=arctan(a+x/1-ax) y = 1/(1+((a+x)/(1-ax))^2) * (1+a^2)/(1-ax)^2 = ... amazing! y=(e^x-e^-x)/(e^x+e^-x) = tanh(x) ...

*November 6, 2016*

**Science**

brain

*November 6, 2016*

**math**

(50/4)*(4-1) = 37.5

*November 6, 2016*

**Physics**

step 1: what is the volume of the cube of ice? step 2: find out how much water is produced when the ice melts. It will decrease in volume by some percentage.

*November 5, 2016*

**Pre-Calculus**

It's the length of u in the direction of the unit vector v/|v|, so u • v/|v|

*November 5, 2016*

**Algebra 2**

log(30,8) = log8/log30 Since the base on the right does not matter, we can use base 10, giving us 3log2/(log2+log3+log5) = 3c/(c+b+a)

*November 5, 2016*

**physics**

volume(cm^3) = mass(g)/density(g/cm^3) so plug in your numbers. I assume you can find the side of a cube, given its volume. (By the way, the length is cm, not cm^3!)

*November 5, 2016*

**algebra**

PV=kT, so PV/T=k is constant. o, you need V such that 30V/330 = 35*20/350 V/11 = 2 V = 22

*November 5, 2016*

**chem.**

If there are x moles of Kr, then there are 2x moles of Ar. Since the number of moles has increased by a factor of 1.47/1.26, 2x+x+.3 = 3x(1.47/1.26) x = 0.6 So, there were originally 1.2 moles of Ar, making the final amount 1.5 moles.

*November 5, 2016*

**Advanced Physics**

Since you don't give any time values, there's no way to figure displacements. Also, the vector does not move; some object does. Also, your explanation is odd. How do you turn southeast? You can turn 30 degrees clockwise, which is toward the SE. Or do you mean that the ...

*November 5, 2016*

**Pre cal**

recall that vertical asymptotes occur when the denominator is zero and the numerator is not. Removable discontinuities are where the fraction is 0/0 Horizontal asymptotes are what happens when x gets huge. f(x) = (x-3)(x+2) -------------- x^2 (x-4) get it now? If not, where do...

*November 5, 2016*

**Math**

If he had d dimes, then he had 3d nickels. So, add up the value of each group of coins: 10d + 5(3d) = 100

*November 5, 2016*

**math**

you can play around with Z table stuff here: http://davidmlane.com/hyperstat/z_table.html

*November 5, 2016*

**algebra**

x = kF x/F is constant. You want F such that 9/F = 10/8

*November 5, 2016*

**Algebra**

or, assuming the usual carelessness with parentheses, (4r+12)/8 = (5r-20)/5 r/2 + 3/2 = r - 4 r = 11

*November 5, 2016*

**math**

24*2+36 = 84 kg flour 50 kg sugar So, now you can figure how many packets of each were made, and thus how many got both.

*November 5, 2016*

**math- Trigonometry**

Look. If cos(x) = 0.8641, you use your cos^-1 button to get x. cos^-1(.8641) = 30.22° sin 30.22° = 0.5033 So, since they gave you the answer in two different ways, as well as a sanity check to see why it makes sense, what is your work, which produces something else? If...

*November 5, 2016*

**sir-reiny-steve help**

assuming all were shot somewhere, (42+43+32) - (5+8+6) + x = 100 Review your Venn diagram material to see why.

*November 5, 2016*

**Math gemetry**

apparently, not to study geometry with a social worker!

*November 5, 2016*

**Math**

#1 ok #2 you have solved 3n = -12 #3 You have solved b/9 = 19 #4 You have solved y-1.8 = 3.18 Did you not check your answers to see whether they actually worked?

*November 5, 2016*

**Math 062**

5642/403 * 3

*November 5, 2016*

**Advance function**

just think back to your Algebra II. Terms of a GP have a common ratio, so tanx/sinx = sin2x/tanx 1/cosx = = 2sinx*cosx * cosx/sinx ...

*November 5, 2016*

**Math**

3 - 1 of each color

*November 5, 2016*

**Math**

suppose there were 40 cows = 160 feet so, you would need 32/2 = 16 fewer cows: 24. The 32 feet would be made up with 16 hens.

*November 5, 2016*

**Adv function**

I think you misplaced a minus sign. Fix it and think "difference of squares"

*November 5, 2016*

**Calculus - huh**

Not what I expected, but quite true. The equilateral triangle has area 4?3 < 8

*November 5, 2016*

**Calculus**

do some setup and I'm sure you will find that the problem is solved by a regular n-gon regardless of the number of sides. Just define the third side in terms of the included angle.

*November 5, 2016*

**Maths**

15.01 15.001 15.0001 17.999 17.99 17.9 I'm sure you can find many more

*November 5, 2016*

**math**

sin(a) cannot exceed 1. Fix your typo and repost.

*November 5, 2016*

**algebra**

.03x + .04y = 170 .04x + .03y = 180 now crank it out.

*November 5, 2016*

**mathematics**

Any point will have its x-coordinate reversed in sign.

*November 5, 2016*

**math**

get numbers add to get sum avg = sum/3 update max and min as the list is read in

*November 5, 2016*

**time speed and distance**

your turn to provide some ideas. We've done several of these for you by now.

*November 5, 2016*

**Maths**

v = pi r^2 h = pi r^2 r ... 2pi r (r+h) = 2pi r(r+h) = 1 ...

*November 5, 2016*

**Maths**

each 1cm layer of water has a volume of 30^2 * 1 = 900 cm^3 So, what's the total volume of the fish? Divide that by 900cm^3 to find how much the water level rises.

*November 5, 2016*

**math**

well, their combined rate is 720/4 = 180 mi/hr

*November 5, 2016*

**science**

convert to moles see how much H2SO4 remains after being neutralized by twice that many moles of KOH. Convert that back to moles/L

*November 4, 2016*

**Calculus Reimann Sum**

so, how did you do it? If the interval is [-2,3] then each interval has length 1, so I fail to see how you got the fraction.

*November 4, 2016*

**algebra 1**

5x-2 passes through (8,38) So, you need to subtract 40 so it goes through (8,-2)

*November 4, 2016*

**Calculus**

Note the sum. You have a2-a1 + a3-a2 + a4-a3 + ... + a21-a20 = a21-a1 = 2^21 - 2^1 There's really no reason to write the sum as you did. Since you know a_i explicitly, it would be better just to say 20 ? 2^(i+1)-2^i i=1

*November 4, 2016*

**Calculus - Special sum formulas**

see your other post. Repeating it does no one any good. Don't forget your Algebra I now that you're taking Calculus!

*November 4, 2016*

**Calculus - Special sum formulas**

Huh? You have the answer. Just simplify if you want: n(n^2-37)/3

*November 4, 2016*

**Pre-algebra**

no. all whole numbers are rational (fractions with denominator=1, as in 2/1, 4/1, etc.) There are lots of numbers that are not rational (irrational), like ?, ?3, ?5, etc. They cannot be expressed as the ratio of two integers.

*November 4, 2016*

**Calculus**

a = 24t+4 v = 12t^2+4t+11 s = 4t^3+2t^2+11t+15 so, s(9) = ?

*November 4, 2016*

**Calculus - Differential Equations**

oh come on. 0+C = -4/6 C = -2/3 -4/u = t - 4/3 u = -4/(t - 4/3) = 12/(4-3t)

*November 4, 2016*

**Calculus - Falling Body Problem**

it is well known that the equations are s(t) = 3000+75t-16t^2 v(t) = 75-32t So plug and chug Extra credit: derive those equations.

*November 4, 2016*

**Calculus - Differential Equations**

so, crank it out: 4 du = u^2 dt 4/u^2 du = dt -4/u = t+C now plug in (0,6) to get C.

*November 4, 2016*

**Tricky Math Question**

However, if you look at the graph for y = x^x the limit near zero is 1. limit x^x log(limit) = x*logx = logx/(1/x) use l'Hospital's rule: = (1/x) / (-1/x^2) = -x log(limit)=0, so limit=1

*November 4, 2016*

**Pre-Algebra**

right Although we're not really using the associative property. That would state that (2.25 • 23) • 4 = 2.25 • (23 • 4) All you did was evaluate the expression inside the parentheses and replace it with an equal value.

*November 4, 2016*

**Math**

well, the floor is 10x16 tiles in size, so ...

*November 4, 2016*

**ss**

well, surely you know that (a) N-S directions are latitude (b) N.A. is west of England...

*November 4, 2016*

**physics**

If ? is the angle upstream, then you have sin? = 2.5/7.3

*November 4, 2016*

**science**

y = tan? x - g/(2 (v cos?)^2) x^2 so plug in your numbers and solve for v when y(10) = 2

*November 4, 2016*

**MATHS**

which area? lateral, total, circular base? I'll assume the base. Volume = base_area * height

*November 4, 2016*

**Physics**

(v^2 sin2?)/g = v^2 sin^2?/g 2sin? cos? = sin^2? 2cos? = sin? tan? = 2

*November 4, 2016*

**Physics**

result of downward and sideways motion.

*November 4, 2016*