Saturday
December 20, 2014

Posts by Reiny


Total # Posts: 28,259

math
1 mechanic can do 4 machines in 6 hours - then 48 mechanic can do 192 machines in 6 hours - then 48 mechanic can do 192(160/6) or 5120 machines in 160 hours
September 7, 2014

geometry
= (1/8)(w)(u + v)
September 7, 2014

Math
5n + 10d + 25q = 12.85 d + q > 2d
September 7, 2014

Math - Urgent
I will rephrase the question: You owe your Mom 10 dollars. You borrow some more and you now owe her $17 How much more did you borrow ?
September 7, 2014

math
A number is divisble by 4 if its two right-most digits are divisible by 4 So our number can only end in 12 , 16, 24, 28, 32, 36, 40, 44, 48, 52, 56, .... , remember that each digit in the whole number is such that it is 1 less than the digit on its right only 56 fits that ...
September 7, 2014

math
m+t+w=39*3 = 117 , (how did you get 108 ?) w+th+f+s = 4*39.5 = 158 add them m+t+2w+th+f+s = 275 , but m+t+w+th+f+s = 9*40= 240 subtract them w = 35
September 7, 2014

Math
bryan ---- x john ----- 2x x + 2x = 1500 solve for x
September 7, 2014

Math
Looks like a clear-cut case of the cosine law, with sides 655(1.5) or 982.5 and 655(2) or 1310 miles and an angle of 170° between them let the third side be x x^2 = 982.5^ + 1310^2 -2(982.5)(1310)cos170° = 5216449.127 x = √ 52.... = 2283.95 miles
September 6, 2014

Geometry
1. yes 2. x = 1 is correct so LM = 6 and MN = 6 which makes M the bisector. You are also right to call M the midpoint, but it asked if M is a bisector. Isn't that basically the same thing? Since "bisect" means cutting into two equal parts.
September 6, 2014

Geometry
Verify you answer by drawing a number line, putting in the values you found or those that were give and "count"
September 6, 2014

Geometry
the midpoint is the "average" of the two values so for the 1st: (4 + (-6))/2 = -2/2 = -1 in the second, you are given the "average" let one of the endpoints be x so (2+x)/2 = -4 multiply by 2 2+x = -8 x = -10
September 6, 2014

Algebra
Bill's rate = 1lawn/45 Jim's rate = 1lawn/75 combined rate = 1lawn/45 + 1lawn/75 = 8lawn/228 time at combined rate = 1lawn/(8lawn/225) = 1lawn (225/8lawn) = 225/8 = 28.125 minutes notice the "lawn" divided out, so we could really have used anything at all. ...
September 6, 2014

Algebra
given: D/A = .8 = 8/10 = 4/5 5D = 4A A = 5D/4 from A = D + E, since we want D/E, why not divide the equation by E to create the D/E in your equation ? A/E = D/E + 1 (5D/4)/E = D/E + 1 5D/(4E) - 4D/(4E) = 1 D/(4E) = 1 D/E = 4
September 6, 2014

Algebra III
To be able to multiply two matrices, the number of columns of the first must match the number of rows of the second For your example that is the true 2 by 3 vs 3 by 5 the result will be 2 by 5
September 6, 2014

COORDINATE GEOMETRY
confusing wording .... You are asking for coordinates of A, but you gave me A as (1,2) (is your cap key stuck? )
September 6, 2014

maths
general term of an AS term(n) = a + (n-1)d for yours a = 25 , d = 2 and n = 10 term(1) = 25 + 9(2) = .......
September 6, 2014

oops - algebra
Sorry, gave you the same link twice should have been this for synthetic division https://www.khanacademy.org/math/algebra2/polynomial_and_rational/synthetic-division/v/synthetic-division
September 6, 2014

algebra
You will need to know "algebraic long division" It is very difficult to show it on this text format, but this webpage has a couple of good examples http://www.sosmath.com/algebra/factor/fac01/fac01.html Try your questions by following the above method If the ...
September 6, 2014

maths
I assume you know the properties of tangents with circles. Join XW and YZ, label their intersection point V XW bisects angle X, and XW right-bisects YZ Label angle WXZ as Ø sinØ = 60/158 = 30/7 Ø = sin^-1 (30/79) Join WZ, where WZ is the radius and we have...
September 6, 2014

algebra 2
This is how I would have expected my students to do this -2(3y-6)+4(5y-8)=92 -6y + 12 + 20y - 32 = 92 14y - 20 = 92 14y = 92 + 20 14y = 112 y = 112/14 y = 8 F = 3r+5 (just a translation of the English to Math) for you last problem isn't p = 10 ? So plug it in and solve the...
September 5, 2014

need answer to check sons work
see previous post If your son does not use variables such as x, you could just pick some arbitrary time, say ... kaye's time is 50 seconds and do what I did in the previous post
September 5, 2014

algebra
create a chart, listing their times: kaye's time ---- t seconds alicia's time ---- t-3.75 carmen's time --- t - 10 donna -------- (t-10) + 5.09 etc you will be able to answer the question
September 5, 2014

Math PLease help
day 1 -- 1 cent = 2^0 day 2 -- 2 cents = 2^1 day 3 -- 2^2 or 4 cents ... day 30 = 2^29 day 31 = 2^30 = 1,073,741,824 cents = $ 10,737,418.24
September 4, 2014

Math-please help!!
let the number of girls be x total in class = x+12 number of students who do not volunteer = (x+12)/2 but this is 15 (x+12)/2 = 15 x+12 = 30 x = 18 So there are 18 girls in the class.
September 4, 2014

math
How did you get that ?? 300(1.04)^5 = 300(1.2166529...) = $364.9959.. = $365.00 to the nearest cent
September 4, 2014

math
number = 300(1.04)^5 = .....
September 4, 2014

algebra 2
gallons of 5% milk --- x .05x + .01(90) = .02(x+90) times 100 5x + 1(90) = 2(x+90) 5x + 90 = 2x + 180 3x = 90 x = 30
September 4, 2014

pre calculus algebra
second number --- x first number = 6x-3 x + 6x-3 = 32 7x = 35 x = 5 one is 5 , the other is 27
September 3, 2014

algrebra
Just sub in the values and do the arithmetic. I will do the harder one x = -3 ...... 4(-3)^2 - 6(-3) + 9 = 36 + 18 + 9 = ....
September 3, 2014

algrebra
it is all done
September 3, 2014

Math
your factored version is incorrect, the last term is wrong 2x(3x^2 + x - 4) = 0 which factors further to 2x(3x + 4(x - 1) = 0 so .. x = 0 or x = -4/3 or x = 1
September 3, 2014

Math
By the "just - look - at - it " theorem, I can see that your solution cannot possible work your answer of 7.93 is appr 8 .69..(8) is about 5.6 1.-3...(8)(.3...) is about 1/3 of 8 or about 2.7 5.6 +2.7 ≠ 63.5... Give it another serious try
September 3, 2014

Math
use your calculator to see if it works for your given equation.
September 3, 2014

Math
suppose you had 4x + 3(7x) = 55 I am sure you could solve that. now follow the same steps for your equation.
September 3, 2014

algebra
Wow, that is some creative algebra I assume your equation is √(2-w) = w , or is it √2 - w = w (notice how my brackets totally change the meaning of the problem) I will assume the first square both sides (√(2-w) )^2 = w^2 2 - w = w^2 w^2 + w - 2 = 0 (w+2)(w-1...
September 3, 2014

Honors Pre Calculus
We could use either a sine or a cosine function, you did not specify which, but I will use sine It must be of the type height = a sin k(Ø + d) + c period = 12 s = 2π/k 2π/k = 12 k = 2π/12 = π/6 also we know a = 25 so far we have height = 25 sin π...
September 3, 2014

algebra 2
f(x) = 4(x-1)^2 - 8 = 4(x^2 - 2x + 1) - 8 = 4x^2 - 8x + 4 - 8 = 4x^2 - 8x - 4
September 3, 2014

algebra
what you meant in your second line was: 8i + 4i^2 + 8i^2 - 2i = 6i + 12i^2 = 6i + 12(-1) = 6i - 12
September 3, 2014

Math
this year: middle : high = 2 : 7 = 2x : 7x 2x = 18 x = 9 so this year we have 18 high and 63 middle for a total of 81 students last year: middle : high = 1:8 = y : 8y but y + 8y = 81 y = 9 So last year we had 9 middle and 72 high school students So difference in high = 72-63 ...
September 3, 2014

math
6x10^24 / 8x10^8 = 7.5x10^15 explanation (6/8) = .75 10^24 / 10^8 = 10^16 so .75 x 10^16 = 7.5 x 10^15
September 3, 2014

Math
two width, each of x one length of y y + 2x = 120 y = 120 - 2x area = xy = x(120-2x) = 120x - 2x^2 1. 120x - 2x^2 = 1350 x^2 - 60x + 675 = 0 (x - 45)(x + 15) = 0 x = 45 or x = -15, the last we will reject if x = 45 , y = 30 2. area = 120 - 2x^2 is a parabola which opens ...
September 2, 2014

Math
depends on the length of the roll, which you did not state Whatever it is, divide it by 2/5 m e.g. suppose it is 30 m long number of pieces = 30/(2/5) = 30(5/2) = 75 pieces
September 2, 2014

Math 112
Right now there are 99 managers. (99 - x)/(100-x) =98/100 9900-100x = 9800-98x -2x = -100 x = 50 check: now there are 99 managers so 50 will leave leabing 49 managers out of the 50 remaining people 49/50 = 98%
September 2, 2014

MA112 HELP PLEASE
Let's look at $1000 after 3 years depreciation of 10% amount = 1000(.9)^3 Then this appreciates for 3 years at 10% final amount = 1000(.9)^3 (1.1)^3 = 970.30 So what do you think?
September 2, 2014

Algebra 2
It means that the answer to your square root is negative. e.g. √25 = 5 but -√25 = -5 not to be confused with √-25 which is not a real number.
September 1, 2014

Algebra 2
Did you not read my reply to your previous question? Do you not have a calculator? ( I needed one to give you the previous answer. )
September 1, 2014

Algebra 2
Depends what accuracy you want. Since 2√5 is irrational, the decimal will not repeat with any definite pattern, nor will it end 2√5 = appr 4.472 correct to 3 decimals or 2√5 = appr 4.47213596 correct to 8 decimal places
September 1, 2014

misread the question
Just noticed the square root part Of what are you taking the square root ? You will need to use brackets, e.g. √(3x + 2y) + 5x = 4 or ... √(3x) + 2y + 5x = 4 or can you see the problem if you don't use brackets ??
September 1, 2014

algebra
3x + 2y +5x=4 8x = 4 - 2y x = (4 - 2y)/8 or x = 1/2 - (1/4)y
September 1, 2014

math homework
Are these feet and inches ?? 8 5/12 + 11 1/4 feet = 236 inches = 236/12 feet = 19 feet, 8 inches or 8 5/12 feet + 11 1/4 feet = 8 5/12 + 11 3/12 = 19 8/12 = 19 feet, 8 inches go metric to avoid such silly arithmetic
September 1, 2014

math
4% reads as " 4 percent" which means " 4 per hundred" = 4/100 = 1/25
September 1, 2014

Math
Assuming the two given points are the endpoints of the hypotenuse, length of hypotenuse = √( (4-2)^2 + (-3-3)^2 ) = √(4 + 36) = √40 or 2√10
September 1, 2014

Pre cal
domain is your choice of x's that will give you a valid y Remember we can't divide by zero so (x+3)(x-1) ≠ 0 so when do we get a zero ? That happens when x = -3 or x=1 so Domain: all values of x except x = -3 or x = 1 2 . The range of a function is the resulting ...
September 1, 2014

Math
c) if x=7 , A = 4.8 ---> (7,4.8) if x = 23, A = 3.2 ---> (23, 2.3) slope = (2.3 - 4.8)/(23-7) = -.1 so A = -.1x + b for one of the points, say (7 , 4.8) 4.8 = -.1(7) + b b = 4.8 + .1(7) = 55 so A = -.1x + 55 your equation from b) has been verified. e. 2.8 = -.1x + 55 .1x...
September 1, 2014

mathzzzzzzzzzzzzzzzzzzzzz i want plzzzzzzzzzzzzzz
number of rows ---- x numbr of people in a row --- x so x^2 = 3249 x = √3249 = 57
September 1, 2014

Math
46/60 = x/40 60x = 1840 x = appr 30.7
September 1, 2014

Calculus
#1 contains a typo, fix the ^0 #2 let the first leg be x cm and the second leg be y cm given: dx/dt = -.5 dy/dt = 2 find: dA/dt , when t = 2 A = (1/2)xy dA/dt = (1/2)(x dy/dt + y dx/dt) at the given time of 2 minutes x = 16 - 2(.5) = 15 y = 12 + 2(2) = 16 dA/dt = (1/2)(15(2...
August 31, 2014

Trigonometry
Look at the first of the "Related Questions" below. The poster had forgotten to give one of the angles and in Steve's solution he called it A. In your problem we know A = 36° so all you have to do is replace A with 36 and go for it. You should get appr 59.86
August 31, 2014

algebra
nothing showing to select from , so let's just solve it -3x^2 + 6x + 9 = 0 x^2 - 2x - 3 = 0 , after dividing by -3 (x-3)(x+1) = 0 x = 3 or x = -1 this must be one of your choices
August 31, 2014

Math
Makes no sense Are you mixing up two different questions?
August 30, 2014

Math
let the height be h m area of floor = 15(12) = 180 m^2 area of ceiling = 180 m^2 area of the 4 walls = 2(15)h + 2(12)h = 54h 54h = 360 h = 20/3 m volume = 12(15)(20/3) = 1200 m^3 (Wow, the ceiling is over 6 m high? very poor design for a classroom)
August 30, 2014

Math
1 acre = 0.4046856 hectares 640 acres = appr 259 hectares or, it depends if you mean a Scottish acre an Irish acre a Cheshire acre or a Roman acre , each of which has a different value, pointing out the silliness of the Imperial system of measurement
August 29, 2014

Calculus 2
y = x^(1/3) y^3 = x y^6 = x^2 Vol = π∫(1^2 - x^2) dy from 0 to 1 = π [ y - y^7 /7] from 0 to 1 = π(1 - 1/7 - 0) = 6π/7
August 29, 2014

math
c^2 = 40^2 + 25^2 = 2225 c = √2225 = appr 47.17 ft
August 29, 2014

probability
Since you are replacing the card, the prob of the first event is the same as the second event prob(your event) = (4/52)(4/52) = 1/169
August 29, 2014

Math
size = a(2)^t , where t is the number of days when t = 30 , size = 6 6 = a(2)^30 a = 6/2^30 1.5 = ( 6/(2^30) )( 2^t) 1.5 = 6 (2^(t-30) ) .25 = 2^(t-30) log .25 = log 2^(t-30) log .25 = (t-30)log 2 log .25/log 2 = t-30 t = log .25/log 2 + 30 = appr 23.356 23 days and 8.5 hours
August 29, 2014

AP Calc. AB
Since you labeled it Calculus, .... dh/dt =56 - .82t when t = 1 dh/dt = 56 - .82(1) =55.18 m/s
August 29, 2014

math
let today's salary be x x(1.04)^30 = 80000 x = $24,665.49
August 29, 2014

math
#1. correct #2. no, you need 7^3/7^5 = 7^-2 , so your choice would be the exponent +3 #3. 2^-5 = 1/2^5 = 1/32 #4. 5^-6 x 5^2 / 5^-8 = 5^-4 / 5^-8 = 5^4 #5 8^-5 / (8^-7)^2 = 8^-5 / 8^-14 = 8^9 mmmh, one correct out of 5, looks like some review of multiplying and dividing powers...
August 29, 2014

Precalculus
width --- x ft length --- x+3 ft 2x + 2(x+3) = 62 take over.
August 29, 2014

statics
So there were 53 boys and 47 girls prob(girl) = 47/100 or .47
August 28, 2014

maths
no -|-4} = -4 |-(-4)| = |4| = 4
August 28, 2014

Calculus
Last time I was on this earth, gravity would cause an equation of the type y = -16t^2 ..... So assuming you have a typo and it should have been y = 35t - 16t^2 Second problem: the ball would not be in the air for 4 seconds, so your whole first question is actually just ...
August 28, 2014

Geometry
strange question, since you say angle AOD = 6x and then angle AOD = 110 So clearly 6x = 110 x = 110/6 = 18 1/3 ° so from that evaluate angle BOC I somehow suspect a typo
August 28, 2014

Geometry
You don't say what kind of figure you are talking about. There are four points mentioned, so you will have to describe the figure
August 28, 2014

math
or the area of the whole board = 11(64) = 704 cm^2 the side is √704 = appr 26.533 cm
August 28, 2014

Advanced Math
1. Written in more "mathematically friendly language" Factor fully: 120 - 36 = 12(10 - 3) 2. - express each number in factored form - Your GCF consists of the products of all the factors found in ALL three numbers e.g. 60 , 84, and 150 60 = 2x2x3x5 84 = 2x2x3x7 150...
August 28, 2014

finance
difference = 5000( 1.09^30 - 1.08^30) = $16,025.11
August 28, 2014

finance
let the payment be P i = .075/12 = .00625 n = 12(30) = 360 P( 1 - 1.00625^-360)/.00625 = 149000 P = 1041.83 So interest = 1041.83(360) - 149000 = $226058.66 (the calculation of total interest paid is really not a realistic actuarial calculation, since we are ignoring the fact ...
August 28, 2014

finance
yes
August 28, 2014

finance
present value = 235( 1 - (1+.0775/12)^-48)/(.0775/12) = $9672.48
August 28, 2014

Math
so you want LW = 120 where L and W are composite , where composite means not prime 120 = (using integers only) 1 x 120 2x60 3x40 * 4x30 * 5x24 6x20 * 8x15 * 10x12 * I have labeled the ones without a prime number with an * so I count 5 of them Your choice of 40 by 4 wouldn'...
August 28, 2014

probability/Geometry
From your data F (Family doctor) = 240 I (inside the US) = 400-130= 270 FI = (2/3)(240) = 160 Make a Venn diagram using a rectangle with two overlapping circles inside, label one F and the other I Place 160 for FI, the intersection of the two circles Place 240-160 or 80 in the...
August 28, 2014

Huhh ? - Intermediate Algebra
32-4-2-16-4 = 6 What is the problem here ?
August 27, 2014

College Algebra
Is there a question? Your equation is correct.
August 27, 2014

math
or Once you have bobpursley's equation of (x-3)^2 + (y+1)^2 = r^2 sub in one of the points on the circle, I will use (-1,3) (-1-3)^2 + (3+1)^2 = r^2 16 + 16 = r^2 = 32 (x-3)^2 + (y-1)^2 = 32 I noticed that bob had the centre as (3,1), should have been (3,-1)
August 27, 2014

trigonometry
For any quadratic equation, if you have irrational or complex roots, they will always come as conjugate pairs, just like your given roots method one: use the fact that if x=a is a root, then x-a will be a factor of your equation, so 1. (x - (2+√5))(x - (2-√5) = 0 (...
August 27, 2014

Check my math please ASAP
#1 is incorrect it should be C think of the number line, -4 is to the right of -9 so -9 < -4 , not > The other three are correct
August 26, 2014

Math
follow the same steps I just showed you in your previous question of this type of problem. Let me know what you get
August 26, 2014

Math 114
Without even checking the answer by substitution, it sound unreasonable right from the start. Since the 588 kg sells for $12 and was mixed from a $11 and a $13 source, we would expect the split to be about half way. 11x + 7644 - 13x = 7056 -2x = -588 x = 294 well, what a ...
August 26, 2014

Math 114
amount of Kenyan coffee --- x amount of Turkish coffee --- 588 11x + 13(588-x) = 12(588) solve for x and you got it
August 26, 2014

Math
let their current salaries be 2x : 3x : 5x new ratios are 2x(1.15) : 3x(1.1) : 5x(1.2) = 2.3x : 3.3x : 6x = 23 : 33 : 60
August 26, 2014

MA
well, let's try it ... a/b = (a+b)/b times b, if b ≠0 a = a+b then b = 0 but now we have a contraction, so ..... or cross - multiply ab = ab + b^2 b^2 = 0 b = 0 , but that would make a/b undefined, so what do you think?
August 25, 2014

math
Don't know what you mean by "work this" The way you typed it, there is no useful simplification. If you meant (6x^2 + 7)/(3x^2 + 1) , there is no useful simplification After a long division you could state the answer as 2 + 5/(3x^2 + 1) , but certainly not what ...
August 25, 2014

Math
don't switch names, I responded you you before http://www.jiskha.com/display.cgi?id=1408984634 The way you have it, the sum is 206 Why is this a difficult question for you, why not just add them up ??
August 25, 2014

Math
I will assume you meant ... x^(log10 x = 100 then by definition: logx 100 = log10x changing to a common base of the log ... log10 100/logx = logx/log1010 2/log10x = log10 x/1 (log10 x)^2 = 2 log10 x =√2 using my calculator x = appr 25.9546 or x = appr .03853 (both ...
August 25, 2014

check (math)
Yup !
August 25, 2014

Math
Is there a typo ? Your first term does not fit the pattern
August 25, 2014

Math
radius of larger circle --- r radius of smaller circle --- r-1 circumf of large ---- 2πr circumf of smaller = 2π(r-10 but 2πr = 4(2π(r-1)) 2πr = 8πr - 8π divide each term by π and rearrange equation -6r = -8 r = 8/6 = 4/3 larger has ...
August 19, 2014

Math
original radius --- r new radius ------ r+1 original area = πr^2 new area = π(r+1)^2 π(r+1)^2 - πr^2 = 16π divide by π and expand ... r^2 + 2r + 1 - r^2 = 16 2r = 15 r = 7/5 units check: old area = π(7.5)^2 = 56.25π new area = π(8.5...
August 19, 2014

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