Tuesday

February 21, 2017
Total # Posts: 48,677

**CAMBRIDGE**

Label the points from left to right: A,P,Q,M,B AP = 2x PB = 3x AQ = 3y QB = 4y PQ = 2 AP+PQ=AQ, so AQ-AP=PQ: 3y-2x = 2 PQ+QB=PB, so PB-QB=PQ: 3x-4y = 2 Solving that, we get y=2, so AB = 7y = 14

*February 21, 2017*

**value**

http://lmgtfy.com/?q=Concept+Of+Special+Interaction

*February 21, 2017*

**math**

twice as many hens can lay twice as many eggs in the same time.

*February 21, 2017*

**Data**

There are 15! ways to arrange the balloons. But, the 5 green balloons can be rearranged in 5! ways that appear the same. Same thing for the other colors. So, you end up with 15!/(5!6!4!) = 630,630 ways

*February 21, 2017*

**Pre Calculus 30**

#1. 5 choices for each digit. So, 5^4 #2. correct #3. 1 * 4^3 #4. 2^3 * 10^4 when repetitions are allowed, you get more choices...

*February 20, 2017*

**Quantitative Reasoning (MATH)**

false the yearly reduction amount decreases with a smaller remaining value.

*February 20, 2017*

**algebra**

25750 * 0.8^5

*February 20, 2017*

**Algebra**

right track, but you made a mistake right at the start: 6z^2 + 40z - 5 = 0 z = (-40±?(40^2+4*6*5))/12 = (-40±?(1600-120))/12 = (-40±?1480)/12 = (-40±2?370)/12 = (-20±?370)/6 z = -0.127 or -6.539

*February 20, 2017*

**Math**

just solve the normal way: C=T/70 +E/30 C + T/70 = E/30 (70C+T)/70 = E/30 E = 30(70C+T)/70 = 3/7 (70C+T) or, E = 30C + 3/7 T

*February 20, 2017*

**Algebra Word Problem**

(x-2)(x+2) = 9+12x x = 13 So, the numbers are 11,13,15

*February 20, 2017*

**math (precalc)**

complex values come in pairs (why?), so the roots are 3-4i, 3+4i, 5, 5 R(x) = (x-(3-4i))(x-(3+4i))(x-5)^2 = ((x-3)+4i)((x-3)-4i)(x-5)^2 = ((x-3)^2+4^2)(x-5)^2 = (x^2-6x+25)(x-5)^2 = x^4 - 16x^3 + 110x^2 - 400x + 625

*February 20, 2017*

**Pre Calculus 30**

#1 First consider all the ways where A&B are together. This is equivalent to permuting 6 students (AB,C,D,E,F,G): 6! = 720. But, we have to double this, since AB and BA are two possible ways that A&B can be together. There are 7! ways to permute the 7 students. 7! - 2*6! = 720...

*February 20, 2017*

**Algebra**

well, did you try the values, to see whether they work? 80*(-1.33)^2 - 96(-1.33) + 27 = 296.192 Hmmm. I'd say nope. So, too bad you didn't show your work... 80x2^ - 96x + 27 =0 Using the quadratic formula, since there are so many possible factors of 80 and 27, x = (96&...

*February 20, 2017*

**Algebra**

If you meant 2.1/(x+1) + 1 4/5 = 3/(10x) then x = -1±?(7/6) If you meant 2.1/(x+1) + 1 4/5 = 3/10 x (5±?77)/2

*February 20, 2017*

**math 1**

a = 2b-8, so (assuming the usual sloppiness with parentheses) 2b-8 = 2/(b-3) (b-4)(b-3) = 1 Now just solve the quadratic. I suspect a typo, just fyi.

*February 20, 2017*

**Algebra**

w(3w-2) = 65 5*13 = 65

*February 20, 2017*

**algebra**

so if the equations involve c and d, what are x and y? The first equation says c-3d = 27 so, c = 3d+27 Use that in the other equation: 4d+10c=120 first, divide by 2 so you can work with smaller numbers: 2d+5c = 60 Now, since c = 3d+27, that means 2d+5(3d+27) = 60 2d+15d+135 = ...

*February 20, 2017*

**Algebra - rats - and the t!**

L2 = (3,7,-11/3) - 4/9 (-3,-3,4)t = (3,7,-11/3) + 4/9 (3,3,-4)t

*February 20, 2017*

**Algebra - oops - lost the n**

L2 is (3,7,k) + n(-3,-3,4)t

*February 20, 2017*

**Algebra**

L1 is (4,2,-3) + (1,3,-2)t L2 is (3,7,k) + (-3,-3,4)t 4+t = 3-3n t 2+3t = 7-3n t 4+t-3 = 2+3t-7 t = 3 n = -4/9 Now we can see that -3-2t = k+4nt -3-2(3) = k+4(-4/9)(3) k = -11/3 L2 = (3,7,-11/3) - 4/9 (-3,-3,4) = (3,7,-11/3) + 4/9 (3,3,-4) at t=3, L1(3) = (4,2,-3) + 3(1,3,-2...

*February 20, 2017*

**physics**

well, it takes 0.4/1.7 = 0.235s to travel that distance. now use your usual equation of motion to find the vertical distance fallen in that time.

*February 20, 2017*

**Algebra/Math**

if it's 8% by weight, then .08 * 150 And the wording should be 150g of an 8% solution

*February 20, 2017*

**Math**

t = u-2 10t+u + 10u+t = 154 154 = 11*14 so t+u=14 the number is 68

*February 20, 2017*

**Math**

try again in English ...

*February 20, 2017*

**math**

review your basic trig functions. Draw a diagram. Note that tan? = 12/19 now you can find ?.

*February 20, 2017*

**Math**

this is just your classic work problem. You started out right, but then went off into the mists. 1/x = 1/40+1/60-1/80 1/x = 7/240 x = 240/7

*February 20, 2017*

**Math**

f = d^2 f+5 = 3(d+5)

*February 20, 2017*

**Math**

2(x+8) = 25 Solve for x, then use to get the area. = 8x

*February 20, 2017*

**math**

36+x = 3(4+x)

*February 20, 2017*

**value**

r^2 = 567/63 = 9 r = ±3 Now you can find a, and S6 = a(r^6-1)/(r-1)

*February 20, 2017*

**Science**

20/(60+20) = 1/4

*February 20, 2017*

**Chemistry**

.28 * 6.023 * 10^23 * 2

*February 20, 2017*

**Algebra**

well, 2 days = 48 hours, so ...

*February 20, 2017*

**Calculus**

#1 swap variables and solve for y: x = ?(3y-2) x^2 = 3y-2 y = (x^2+2)/3 now f(x) has domain: x >= 2/3 range: y >= 0 f^-1(x) has domain: x >= 0 range: y >= 2/3 because f(x) has only one branch #2 f(x) = ?[1,x] sin(t)/t dt I don't think you want f(x), because it ...

*February 19, 2017*

**Math 104**

5P2 = ?

*February 19, 2017*

**math**

(2,3) [2,3]

*February 19, 2017*

**Algebra2**

write a recursive formula for the sequence 5,18,31,44,57 then find the next term. My answer is a1=5,an=an-1+13 The next term would be 70.

*February 19, 2017*

**Calculus II**

google the topic and you will find many discussions and examples. For a region of uniform density, the center of mass is the same as the centroid.

*February 19, 2017*

**Pre-Calculus**

3 = 2.1 sin[(?/6)t - 5?/6] + 3.2 2.1 sin[(?/6)t - 5?/6] = -0.2 sin[(?/6)t - 5?/6] = -0.095238 (?/6)t - 5?/6 = -.0953826 (?/6)t = 2.522611 t = 4.8178 and of course, there is another solution

*February 19, 2017*

**Math**

9.50a + 5.50(148-a) = 1170.00

*February 19, 2017*

**Algebra2**

thank you

*February 19, 2017*

**Algebra2**

cd = k a constant. So, you want d such that 86d = 2*17

*February 19, 2017*

**Algebra2**

suppose c and d vary inversely and d=2 when c=17 write an equation that models that variation find d when c=68

*February 19, 2017*

**Algebra2**

note that xy = 10

*February 19, 2017*

**Algebra2**

Does the relation in the table represent direct variation, inverse variation, or neither? if it is direct or inverse variation, write an equation to represent the situation. Explain your answer x 5, 10, 15, 20 Y 2, 1, 2/3, 1/2

*February 19, 2017*

**MATH**

15/(10+15) = 3/5 = 60%

*February 19, 2017*

**Maths bearing**

use the law of cosines.

*February 19, 2017*

**Math**

use the law of cosines.

*February 19, 2017*

**Math**

I'd guess the same, if it's in the same circle ...

*February 19, 2017*

**Differential equation**

?? Just plug in the numbers: at r=3, dr/dt = 5?/36 = k/9 k = 5?/4

*February 19, 2017*

**Math**

since 1 revolution is 360 degrees, (25 * 2? ft/rev) * (2?/10 rev/s) * 3600s/hr * 1mi/5280 ft = 10.71 mi/hr

*February 19, 2017*

**Math**

looks like it already is!

*February 19, 2017*

**math**

subtract the area of the lawn from the total area including path: (50+16)(40+16)-50*40 = ?

*February 19, 2017*

**fractionss**

2/3 * 1/2 ordered dessert

*February 19, 2017*

**fractions**

the amount left was (1 - 4/7)(1 - 2/5) = 3/7 * 3/5 = 9/35 of the original amount. So, 9/35 x = 9 x = 35

*February 19, 2017*

**Differential equations**

yes indeed

*February 19, 2017*

**Maths**

3*2*(120+68) = 1128m

*February 19, 2017*

**math**

read this and follow the example. What do you get? Hint: the curve looks like a straight line to me ...

*February 18, 2017*

**Math**

hard to say, with no diagram and no description...

*February 18, 2017*

**Math**

.60*70 + x*40 = .70*110 x = .875 so, they must win 7/8 * 40 = 35 of the remaining games. Good luck with that...

*February 18, 2017*

**math**

x=1, so A=1+2+1 = 4 ...

*February 18, 2017*

**Math**

-1/8 (x+35)= -7 x+35 = -7(-8) = 56 x = 21

*February 18, 2017*

**calculus**

E = IR dE/dt = R dI/dt + I dR/dt If E is constant, then dE/dt = 0 if R=20, then I = 5, so you can use that in the formula above. Naturally, if R is increasing, the current is decreasing.

*February 18, 2017*

**physics**

geez - you have the equation - plug in the numbers.

*February 18, 2017*

**math**

D is the lateral area. If you include the base, then you get choice B

*February 18, 2017*

**algebra**

y(x(t)) = ln(2x(t)) = ln (2*3e^(t/1.7)) = ln6 + ln e^(t/1.7) = t/1.7 + ln6

*February 18, 2017*

**Algebra**

google is your friend. This is but one of many discussions on the topic. http://www.web-formulas.com/math_formulas/geometry_surface_of_cone.aspx

*February 18, 2017*

**science**

resistance = (resistivity * length)/area so, just plug in your numbers... watch the units.

*February 18, 2017*

**Math**

That's what I get, too.

*February 18, 2017*

**science**

You need 2 H for each CO3, so 2HCl + K2CO3 -> 2KCl + H2CO3

*February 18, 2017*

**electronic**

sounds like you just have to plug in the numbers ...

*February 18, 2017*

**MATH**

As Crocodile Dundee would say, Now that's a detour! (eh?)

*February 18, 2017*

**MATH**

cosA = 1/2 A = ?/3 4A = 4?/3 cos4A = -1/2

*February 18, 2017*

**Science**

NO is 2/5 of the output of 10 moles. Since the original 9 moles occupied 27 liters, the 10 moles occupy 30 liters. So, NO occupies 2/5 * 30 = 12 liters. This assumes that the H2O is also a vapor.

*February 18, 2017*

**Algebra**

2x+2y = 28 so, y=14-x for the area, a = xy = x(14-x) This is just a parabola,so find its vertex.

*February 17, 2017*

**Math**

what were the possible scores on the dart board?

*February 17, 2017*

**Math**

yes.

*February 17, 2017*

**Physics**

23 * 24 * 8/1000 = 4.4¢

*February 17, 2017*

**um**

at wolframalpha.com, type in arctan(8) Or, learn to use your calculator ...

*February 17, 2017*

**precalculus**

e^(.08t) = 2 The initial amount does not matter.

*February 17, 2017*

**geometry**

in a 30-60-90 right triangle, the ratio of the sides is 1:?3:2 m?L = 30°, so the short leg is 9. The sides are thus 9,9?3,18 and the perimeter is 27+9?3 Looks like you need to review the standard triangles...

*February 17, 2017*

**geometry**

note that in a 45-45-90 right triangle, the sides are in the ratios 1:1:?2 So, draw the figure, label the known side, and then you can get the others.

*February 17, 2017*

**physical science**

more likely, something metric ...

*February 17, 2017*

**Esol**

correct.

*February 17, 2017*

**math**

uh, I'd guess 20/8

*February 17, 2017*

**Algebra**

f(x) = -5(3^x) f(0) = -5(3^0) = -5(1) = -5 f(1) = -5(3^1) = -5(3) = -15 f(2) = -5(3^2) = -5(9) = -45 the graph is at http://www.wolframalpha.com/input/?i=-5(3%5Ex)

*February 17, 2017*

**Geometry**

PN^2 = 17^2-15^2 = 64 PN = 8 So, NQ = 39-8 = 31 QR^2 = 31^2+15^2 = 1186 QR = 34.438

*February 17, 2017*

**Math**

Alkesh borrowed -- x Sanjay borrowed -- 2x So, how much interest did Sanjay pay? see where that takes you. (I think the actual question is garbled...)

*February 17, 2017*

**math**

A = ?ab Note that for a circle, a=b, so A = ?a^2

*February 17, 2017*

**math**

dy/dt = y/4 dy/y = 1/44 dt lny = t/4 + c y = c*e^(t/4) y(0)=20, so c*e^0 = 10 c = 20 y = 20e^(t/4) You are correct.

*February 17, 2017*

**Geometry**

since the diagonals bisect each other, AE = EC 3x+12 = 27 ...

*February 17, 2017*

**Vector**

Assuming it is in the same direction, then if p is the vector to P, then p+v = [-11,-1] Q = (-11,-1) Q could also be the end point of p-v.

*February 17, 2017*

**math**

"more" means you are going to add. Add what to what?

*February 17, 2017*

**Math**

4.75 = 4 3/4 = 19/4 6 1/8 = 49/8 6.3 = 63/10 10 1/2 = 21/2

*February 17, 2017*

**Stat**

2(26^2 + 26^3) = ?

*February 17, 2017*

**Algebra**

(x-1/2)-(x-2/2)+(x-3/2)-...-(x-100/2) x-x+x-x+...+x-x - 1/2 + 2/2 - 3/2 + ... - 99/2 + 100/2 the x-x+x-x terms cancel out, and we are left with 1/2 (-1+2 -3+4 ... -99+100) = 1/2 (1+1...+1) (50 times) = 1/2 * 50 = 25

*February 17, 2017*

**Maths**

first, how is the "rank" of a word defined?

*February 16, 2017*

**Math**

$22/player, so ...

*February 16, 2017*

**Statistics**

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

*February 16, 2017*

**math**

using similar triangles, if he is x meters from the tree, (x+3.5)/28 = 3.5/1.5

*February 16, 2017*