Friday
July 1, 2016

Posts by Reiny

Total # Posts: 35,112

sequences and Series
I have now answered 6 of your questions without any effort on your part showing me that you have attempted these. What do you think about this one? Why not just follow the rules of the sequence as you stated them?
April 21, 2016

Maths
Ok so far simplify your expression a bit and use proper brackets = 11Ck (1/4)^(11-k) (-16)^k x^(11-k) y^k so y^k <----> y^4 thus k = 4 the coefficient comes from 11Ck (1/4)^(11-k) (-16)^k = 11C4 (1/4)^7 (-16)^4 = 330(1/16384)(65536) = 1320 confirmation: https://www....
April 21, 2016

sequences and Series
geeesh, why not just list the berries handed out for each house? There are only 5 identical steps
April 21, 2016

Sequences and Series
appears to go 6,5,1,2 ..... a cycle of 4 terms. the 21st term must be 6
April 21, 2016

Sequences and Series
add 1 to each even numbered term add 5 to each odd numbered term 25,5,30,6,35,7,40,8,45,...
April 21, 2016

Series and Sequences
Not enough data to tell for the first 3, there is an increase of 20 from one to the other for the last three, there is the same increase but we can't tell what happened from term3 to term4
April 21, 2016

please math help
T/F ---- x multiple choice --- y x+y = 20 ----> y = 20-x 3x + 11y = 100 3x + 11(20-x) = 100 3x + 220 - 11x = 100 -8x = -120 x = 15 and then y = 5 There are 5 multiple choice questions
April 21, 2016

Math linear equations
large pitcher --- x small pitcher --- y x + 2y = 8 x - y = 2 subtract them: 3y = 6 y = 2 then x = 4 large holds 4 cups, the smaller holds 2 cups
April 21, 2016

Math
radius of circle = 1450 ft circumference of whole track = 2π(1450) = 2900π ft angle of sector between them = 90 + arctan(1440/170) = 173.267° Distance Robin has to make up is 173.267/360 = x/2900π x = 4384.9155 ft He is gaining on him at a rate of 1.3 ft/sec...
April 20, 2016

Math
prob(grow) = .65 prob(not grow) = .35 prob(1 of 11 will not grow) = C(11,1)(.35)(.65)^10 = .05183
April 20, 2016

NEED HELP MATH QUESTION ASAP
Prob(rolling a two) = 1/6 number of expected times of getting a 2 in 6 rolls = 6(1/6) = 1
April 20, 2016

Math
I assume you meant:Volume = 4(c)^3(b)^8 Base area = 16(ab)^3 let the height be h h(16(ab)^3) = 64(c)^3(b)^8 h = 4 c^3 b^5 /a^3 No choice is correct
April 19, 2016

math
age of son ---- x age of woman --- 4x 5 years from now: son : x+5 woman : 4x+5 4x+5 = 3(x+5) solve for x
April 18, 2016

Trig
This same post has been declared as muddled and garbled several times. It has been answered by both Steve and I and you should not expect any more replies until you fix the wording so that the question makes sense http://www.jiskha.com/display.cgi?id=1460596777
April 18, 2016

Math/algebra
Cutting through the chase: 60 + -25x = 35x + 20 -25x - 35x = 20 - 60 -60x = -40 x = 40/60 = 2/3
April 18, 2016

Trigonometry
draw your triangles in the correct quadrantIs. Use Pythagoras in each case. if cosu = 3/5, in IV, then sinu = -4/5 if cosv = 12/13, then sinv = -5/13 sin(u-v) = sinu cosv - cosu sinv = (-4/5)(12/13) -(3/5)(-5/13) = (-48 + 15)/65 = -33/65
April 17, 2016

Ms Sue please helpp
4356/9999 = 484/1111
April 17, 2016

Algebra
x y 1stdiff -- 2nddiff 0 4 1 5 -- 1 ----- 2 8 -- 3 ----- 2 3 13 --5 ----- 2 4 20 --7 ----- 2 since the 2nd difference is a constant, it must be a quadratic, or 2nd degree function
April 15, 2016

Algebra
take 1/2 of the coefficient of the middle term, then square it, so c = 169/4
April 15, 2016

Algebra
rate of smaller pipe --- 1/x rate of larger pipe ---- 1/(x-18) , where x > 18 combined rate = (x-18 + x)/(x(x-18) = (2x-18)/(x^2 - 18x) 1/[(2x-18)/(x^2 - 18x)] = 12 x^2 - 18x = 24x - 216 x^2 - 42x + 216 = 0 (x - 36)(x - 6)= 0 x = 36 or x = 6 but x = 6 does not fall into my ...
April 15, 2016

Algebra
http://www.jiskha.com/display.cgi?id=1460741071
April 15, 2016

Algebra
look below at Related Questions for variations of your question. Simply change the numbers in the solution by Henry
April 15, 2016

Algebra
your equation should be s = -4t^2 - 6t + 100 you want to know when s = 0 4t^2 + 6t - 100 = 0 2t^2 + 3t - 50 = 0 t = (-3 ±√409)/4 = appr 4.3 seconds or a negative, which we will reject
April 15, 2016

Algebra
speed of slower plane --- x km/h speed of faster plane --- x+50 km/h 1400/x - 1000/(x+50) = 3 times x(x+50) 1400(x+50) - 1000x = 3x(x+50) 1400x + 70000 - 1000x = 3x^2+ 150x 3x^2 - 250x - 70000 = 0 (x - 200)(3x + 350) = 0 x = 200 or a negative, which is rejected The slower ...
April 15, 2016

math
In the first case I would be dividing both sides by -4 In the second equation I would be multiplying both sides by -4 the two answers differ by a factor of 16
April 15, 2016

math
you are welcome
April 15, 2016

math
From some starting point, draw 5 lines downwards. From the end of each of those lines, branch off 3 more lines each There should now be 15 endpoints.
April 15, 2016

maths
Confirming Steve's conclusion: https://www.wolframalpha.com/input/?i=Plot+y+%3D+e%5Ex,+y+%3D+x
April 15, 2016

engineering mathematics
let f(x) = x^3 - 6x^2 + 13x - 9 f'(x) = 3x^2 - 12x + 13 xnew = x - f(x)/f'(x) = x - (x^3 - 6x^2 + 13x - 9)/(3x^2 - 12x + 13) = (3x^3 - 12x^2 + 13x - x^3 + 6x^2 - 13x + 9)/(3x^2 - 12x + 13) = (2x^3 - 6x + 9)/(3x^2 - 12x + 13) using my calculator, with an initial guess ...
April 15, 2016

math
for a fun topic along these lines, Google and look into the "chinese remainder theorem"
April 14, 2016

math
So the number must be such that when divided by 3 , leaves a remainder of 1 when divided by 4 , leaves a remainder of 1 when divided by 5 , leaves a remainder of 1 Find the lowest common number is these sets: 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64..... 5 ...
April 14, 2016

algeabra
x+7 divided by x-4 = 1 + 11/(x-4) test by adding 1 + 11(x-4)
April 14, 2016

maths
Jake --- x Ken ---- 4x giveaway: Jake --- x+360 Ken ---- 4x-360 4x-360 >= x+360 3x >= 720 x >= 240 Ken >= 600 The least Ken will have is 600
April 14, 2016

mathematics-combination vs A.P
then n!/(5!(n-5)!) - n!/(4!(n-4)!) = n!/(6!(n-6)! - n!/(5!(n-5)!) divide each term by n! and re-arrange 2/(5!(n-5)!) - 1/(4!(n-4)!) = 1/(6!(n-6)!) realize that 6!=6x5x4! and (n-4)! = (n-4)(n-5)(n-6)! 5!=5x4! and (n-5)! = (n-5)(n-6)! multiply each term by 6!(n-4)! 2(6)(n-4) - (...
April 14, 2016

Statisitcs
Use the same formula you have to find the z-score I don't know if you use tables from the back of a textbook, or some webpage like David Lane's fabulous page http://davidmlane.com/hyperstat/z_table.html suppose that the percentage of Alice getting a mark of 75 or less ...
April 14, 2016

Math
John's rate = room/3 Apprent's rate = room/6 combined rate = room/2 + room/6 = 3room/6 = room/2 time at combined rate = room/(room/2)) = 1/(1/2) = 2 hours
April 14, 2016

Disagree - MATH I DONT UNDERSTAND PLZ HELP ASAP THX= }
At 6:00 am, the temperature was -20° C after having risen 8° since midnight So at midnight it was -28° (years ago that would have been just a nippy night. These last few years it never got that cold in my part of Canada)
April 13, 2016

calculus 1
let the radius be r and let the height be h πr^2 h = 2000π h = 2000/r^2 we want to minimize the surface area A A = 2πr^2 + 2πrh = 2πr^2 + 2πr(2000/r^2) = 2πr^2 + 4000π/r dA/dr = 4πr - 4000π/r^2 = 0 for a minimum of A 4πr...
April 13, 2016

Precalculus(another)
The wording is quite muddled in the middle of your post. However, I think we have a cosine law problem here, with sides 12 and 5 and the contained angle as 37 degrees d = 12^2 + 5^2 - 2(12)(5)cos37 = ....
April 13, 2016

Precalculus
I assume you only want the length of the cable going down the hill. Make a sketch. On mine I have a triangle with sides 100 and 95 with an angle of 102 degrees between them. The cosine law is just screaming at you here. x^2 = 100^2 + 95^2 - 2(100)(95)cos102 = .... you do the ...
April 13, 2016

CONSUMER MATH
I assume the $12,000 is the present value i = .039/12 = .00325 n = 6(12) = 72 Payment = p p( 1 - 1.00325^-72)/.00325 = 12000 solve for p
April 13, 2016

Math
If 1/4 inches ---> 1 ft then 1 inch -----> 4 ft and 3 inches ---> 12 ft
April 13, 2016

Math
Make a sketch, extend the line from the top of the tower to the man until it hits the base line You now have a small isosceles right-angled triange within a larger one. so the smaller one has legs 1.4 m and 1.4 m. So the base of the larger is 1.4+10 or 11.4 m, which means that...
April 13, 2016

Damon,steve,reiny,bobpursley....Any 1 just help me plz
That's just plain silly.
April 13, 2016

Geometry
You want the lateral surface area of a cone = π r s, where r is the radius, and s is the "slant" height = π(25)(32) = cm^2
April 13, 2016

Algebra
This is a GP where a = 26000 and r = 1.03 sum(5) = 26000(1.03^5 - 1)/(1/03-1 = $138,037.53
April 13, 2016

Algebra 2
if you want your index to be n = 0 , then 9 Σ 2(n+1) n=0
April 13, 2016

Algebra 2
10 Σ 2n n = 1
April 13, 2016

Probability
I did the first two for the last two , you are dealing with conditional probability Prob( B given A) = prob(B|A) = prob(A and A)/prob(A)
April 13, 2016

oops - Math
ignore my previous answers, I totally forgot about the actual probabilities. so for prob(makes first misses seconds and third shots) = (7/10)(3/10)(3/10) = 63/1000 or .063 prob(missing all 3) = (3/10)^3 = 27/1000 so prob(of making at least one shot) = 1 - 27/1000 = 973/1000...
April 13, 2016

Math
h -- hit m -- miss she has the following cases: hhh hhm hmh mhh hmm * mhm mmh mmm "makes first misses seconds and third shots " --- I see one case, marked with * so prob(hmm) = 1/8 "Makes at least 1 shot" all except mmm so prob(of that event) = 1 - 1/8 = 7/8
April 13, 2016

Math
No common ratio, thus no geometric sequence however the 2nd, 3rd and 4th form the pattern: -(consecutive even)^2 but then the first term does not follow this pattern. I don't see anything else
April 13, 2016

Trig
You should memorize the trig ratios is terms of x, y and r so for the point (-1,3) x = -1, y = 3 and by Pythagoras, r = √10 cosθ = x/r = -1/√10 and since secθ = 1/cosθ secθ = -√10
April 13, 2016

math
There are 3 such multiples, 6,12, and 18 prob(of your event) = 3/18 = 1/6
April 13, 2016

Math
Are we answering only c) ? c) since there are only reds and whites, and you want prob(red OR white) the prob(red OR white) = 1 that is, 2/10 + 8/10 = 10/10 = 1
April 13, 2016

Calculus Answer Confirming Not Sure Im Right Help?
For the given substitution , the two statements: lim (∛x-4)/(x-64) , as x --->64 and lim (u - 4)/(u^3 - 64) , as u ---> 4 are equivalent, so lim (∛x-4)/(x-64) , as x --->64 = 1/48 and lim (u - 4)/(u^3 - 64) , as u ---> 4 = 48 They are equivalent ...
April 12, 2016

Calculus Answer Confirming Not Sure Im Right Help?
let ∛x = u then x = u^3 and as x---> 64, u ---> 4 lim (∛x-4)/(x-64) , as x --->64 = lim (u - 4)/(u^3 - 64) , as u ---> 4 = lim (u-4)((u-4)(u^2 + 4u + 16) , u -->4 = lim 1/(u^2 + 4u + 16), as u --> 4 = 1/(16 + 16 + 16) = 1/48 When you make your ...
April 12, 2016

IMPORTIANT MATH
let the width be x let the length be y, along the wall so 2x + y = 75 y = 75-2x area = xy = 600 x(75 - 2x) = 600 -2x^2 + 75x = 600 x^2 - 37.5x = -300 x^2 - 37.5x + 351.5625 = -300 + 351.5625 (x - 18.75)^2 = 51.5625 x - 18.75 = appr 7.18 x = appr 25.93 y = 23.139
April 12, 2016

Math
I ask myself, "how far from the x-axis is my given angle" After I decide which quadrants the given angle is in, I go in II: 180 - angle in III: angle - 180 in IV: 360 - angle e.g. for 330° , which is in IV reference angle = 360-330 = 30° ... for 203, which is...
April 12, 2016

Math
area of yard = (14x)(19x) = 266x^2 area of circle = π(36x^2) area of remaining yard = 266x^2 - 36πx^2 = (266-36π)x^2
April 12, 2016

Math
let the monthly rate be i 614( 1 - (1+i)^-48)/i = 24905 (1 - (1+i)^-48)/i = 40.56189 that's toughie to solve, I will use Wolfram https://www.wolframalpha.com/input/?i=solve+614(+1+-+(1%2Bx)%5E-48)%2Fx+%3D+24905 i = .00709 so the annual rate compounded monthly = 12(.00709...
April 12, 2016

finance math
not that simple let the monthly rate be i 614 (1 - (1+i)^-48)/i = 24905 very tough to solve I will let Wolfram do it https://www.wolframalpha.com/input/?i=sove+614+(1+-+(1%2Bx)%5E-48)%2Fx+%3D+24905 i= .00709283 12i = .08511... or 8.511% per annum compounded monthly
April 12, 2016

algebra
amt = 800(1.02^22 - 1)/.02 = ....
April 12, 2016

Math question help!!
Two interpretations are possible for this question. 1. There are 24 students in the class like you said. So if 1/3 are missing, then there are 8 missing, just like Ms Sue had in her previous post. 2. With 1/3 missing, there are 24 students in the class, so the 24 students ...
April 12, 2016

math
Only A and B make sense although at the end of A , you probably meant to say 4 people at round table
April 12, 2016

Algebra
width --- x length --- 4x area = x(4x) = 36 4x^2 = 36 x^2 = 9 x = 3 the room is 3 m by 12 m
April 12, 2016

Algebra
smaller tile --- x by x larger tile ---- x+4 by x+4 x^2 + (x+4)^2 = 40 expand and solve as a quadratic equation. it will factor and solves easily.
April 12, 2016

Algebra
thoko ---x zandile -- x+4 4 years ago: thoko -- x-4 zandile -- x x(x-4) = 165 x^2 - 4x - 165 = 0 (x-15)(x+11) x = 15 or x = -11 state the conclusion
April 12, 2016

Algebra
".A student is 6 times younger than her teacher" --> usually stated as, teacher is 6 times older than the student age of student --- x age of teacher ---- 6x 3 years ago: student : x-3 teacher : 6x-3 (x-3)(6x-3) = 36 6x^2 - 21x + 9 - 36 = 0 6x^2 - 21x - 27 = 0 2x^...
April 12, 2016

finance
amount = 4000( 1.105^5 - 1)/.105 = ...
April 12, 2016

Algebra, math
Nothing as serious as when WKRP's Les Nessman reported live turkey's dropping from the sky. "As God is my witness, I thought turkeys could fly!!!" -- Arthur Carlson, WKRP in Cincinnati
April 12, 2016

math
let the unit digit be x let the middle digit be k let the hundred digit be y the original number = 100y + 10k + x the number reversed = 100x + 10k + y so 100x + 10k + y = 100y + 10k + x 99x = 99y x = y We sort of knew that so it doesn't matter what we put in the middle to ...
April 12, 2016

Trigonometry
a) if the cone is 8 inches high and it is filled with a depth of 8 inches, then the cone is full of water, and the radius of the water level must be 4 inches. Is there a typo here? b) let the height of the water be h, and the radius of the water level be r by similar triangles...
April 12, 2016

math
You are correct with A = w(w+3)
April 12, 2016

Math
first year -- 4 = 2(2^1) 2nd year ---- 8 = 2(2^2) 3rd year ---- 16= 2(2^3) can you see the pattern ... 10th year ----- 2(2^10) = 2048 you were right! Did you do it in a different way?
April 12, 2016

Math Help!
remember, when you divide powers with the same base, keep the base and subtract the exponents, so 7^9/7^3 = 7^9 ÷ 7^3 = ...
April 12, 2016

College Algebra
No idea what the Malthusian model is, but I will do it my way P = 30,000 e^(kt) , where k is constant and t is years given:when t = 9, P = 60,000 30000 e^(9k) = 60000 e^(9k) = 2 9k = ln2 k = ln2/9 P = 30,000 e^((ln2/9)t) when is P = 1,000,000 ? 30,000 e^((ln2/9)t) = 1,000,000 ...
April 12, 2016

Calculus I
V = (4/3)π r^3 dV/dt = 4π r^2 dr/dt given: dV/dt = 8π , r = 1 8π = 4π(1) dr/dt dr/dt = 8π/4π = 2 A = 4πr^2 ----> (did you notice that surface area equals the derivative of volume ??) dA/dt = 8πr dr/dt when r = 1 dA/dt = 8π(1...
April 12, 2016

Math Help!
You are very welcome
April 12, 2016

Math Help!
correct for both
April 12, 2016

Math Help!
I noticed in your first question you have 4^a. None of the choices would match that. It had to be 2a(a^2 + 4a) to get a correct answer from your choices. You are using the distributive property which is illustrated by a(b + c) = ab + ac you multiply the stuff sitting in front ...
April 12, 2016

Algebra
Let the completed job be represented by 1 The first crew worked for 2 days, so they did 2/7 of the job. This leaves 5/7 of the job to be finished by the combined work of the two crews rate of first crew = 1/7 rate of 2nd crew = 1/5 combined rate = 1/7 + 1/5 = 12/35 let the ...
April 12, 2016

Math
XXXXXX 000901 This follows your wording, but a number such as 000901 would be 901, making it a 3 digit number. Does you number have decimals? then how about 901.000 ? Otherwise your question makes no sense
April 12, 2016

Algebra
Did you translate the English into Math? I said: x^2 = 4x + 60 now you have a nice and simple quadratic which factors. x^2 - 4x - 60 = 0 solve for x, and take only the positive result
April 12, 2016

Math
You obviously have a ||gram WXYZ where angle X = 113 In any parallogram, the opposite angles are equal and adjacent angles add up to 180 I don't know what <XYZ= <YZW= <ZWX= is supposed to mean. If 3 angles are to be equal then you must have a rectangle, which ...
April 12, 2016

algebra
see here http://www.jiskha.com/display.cgi?id=1460427888 Give yourself a nickname, so we can keep track of the questions and avoid duplication.
April 11, 2016

EASY Pre-Algebra
the four offices are defined and distinct. e.g, you could not simply interchange the office of the secretary with the office of the chairman So you have a permutation, since the order matters. Words such as "committee, select, choose" usually imply a combination
April 11, 2016

Calculus Help Stuck Part 2?
careful: what happened to your x's in (x-4)/(4-x) ? What really happened is this (x-4)/(4-x) = -1(4-x)/(4-x) = -1[ (4-x)/(4-x) ] = -1[ 1 ] = -1 Any number divided by its opposite = -1
April 11, 2016

Calculus Help Stuck Part 2?
Step1 for me in any limit question is actually sub in the approach value If you get a real number, that's your answer, all done! so for x = 4, we get 0/0, ok, we got work to do step: if you get 0/0 for simple rational expressions like the above, IT WILL FACTOR. Sometimes ...
April 11, 2016

maths
cosa = 12/13 construct a right-angled triangle and use Pythagoras to find the sides 5, 12, and 13 since the cosine is + in I or IV, we have two cases: case1: in quad I sina = 5/13, cosa = 12/13 seca + sina = 13/12 + 5/13 = 229/156 case2: in quad IV sina = -5/13, cosa = 12/13 ...
April 11, 2016

interest rates computation
first investment --- x 2nd investment ----- 4x .07x + .13(4x) = 7965 solve for x
April 11, 2016

algebra
Follow the same steps I showed you in the previous post Same kind of problem.
April 11, 2016

algebra
looks like everything is referenced in terms of quarters, so start with : let the number of quarters be x dimes ---- x+138 nickels ---- 2x pennies ---- 14x + 28 Now that you have the NUMBER of coins defined, we go for the VALUE of those coins 25x + 10(x+138) + 5(2x) + 1(14x+28...
April 11, 2016

Math
total ages = 60 Generally, if the mode is 8 would mean there are more than one age of 8 suppose there are two with age 8, leaving 44 for the other 4 (11 for the average of the remaining 4) could have 9 and 13, and 8 and 14 so we could have: 8,8,8,9,13,14 or we could have: 8,8,...
April 11, 2016

Calculus
go to your other post further up
April 11, 2016

Calculus
at x = 5, we get 20/0 which is undefined The limit does not exist (we only have work to do if the limiting value produces 0/0)
April 11, 2016

Math
Haven't seen anybody use tables out of "handbooks" in over 30 years, .... amount = 9000(1.08^20 - 1)/.08 = 9000(45.7619643) ---> last number should be in your handbook = $411,857.68
April 11, 2016

Math
A blue car cannot be on either end. So we have to start and end with a red car. They must be parked this way RBRBRBR number of way to do this is R-B-R-B-R-B-R 4x3x3x2x2x1x1 = 144
April 11, 2016

Word problem middle school
This looks like a GP with a = 4 r = 1.5 so cost = 4 + 4(1.5) + 4(1.5)^2 = ... I will let you do the arithmetic
April 11, 2016

Bus. Math help!
So PV = 80,000 i = .085/12 = .0070833333.... n = 12(25) = 300 payment = x x(1 - 1.00708333..^-300)/.00708333...) = 80,000 x = 644.18 which is none of the choices, D would come closest
April 11, 2016

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