Monday
May 30, 2016

Posts by Reiny

Total # Posts: 34,826

Math- 2 questions!
correct
February 19, 2016

Algebra
amount in B -- x amount in A -- 3x .06(3x) + .07x = 2250 .18x + .07x = 2250 .25x = 2250 x = 9000 so $9000 in B and $27,000 in A
February 18, 2016

Finance
What about the initial $25,000 that he starts with ? i = .06/12 = .005 25000(1.005)^324 + R(1.005^324 - 1)/.005 = 1,000,000 R(806.5468...) = 874,181.64 R = $1083.86
February 18, 2016

Math
hard to draw trees here, will do it in listing form we want E to win, as soon as they win 2 games it is all over, no more than 3 games Possible ways: EE = .6^2 = .36 ERE = .6(.4)(.6) = .144 REE = .144 prob = sum of those = .648
February 18, 2016

Pre-Calculus
solve each for t x = 9t+2 9t = x-2 t = (x-2)/9 y = 2t-2 2t = y+2 t = (y+2)/2 so (x-2)/9 = (y+2/2 cross-multiply 2x - 4 = 9y + 18 2x - 9y = 22--> I would have like that from -9y = -2x + 22 y = (2/9)x - 22/9 -- looks like the a)'s have it.
February 18, 2016

Algebra
width ---- x m length ---- x+30 320 < 2x + 2(x+30) < 360 320 < 4x + 60 < 360 260 < 4x < 300 65 < x < 75
February 18, 2016

algebra
#2 - ok #3 x/5+6=10 x/5=4 x = 20 #4 -2(m-30) = -6m -2m + 60 = -6m 4m = -60 m = -15 #5 3.75x+3.7=1.7+1.75x 2x = -2 x = -1
February 18, 2016

math
number of ways to choose 10 from 22 = C(22,10) what can't we have: choosing 5 plays + choosing 6 plays = C(6,5)xC(16,5) + C(6,6)xC(16,4) number of ways = C(22,10) - ( C(6,5)xC(16,5) + C(6,6)xC(16,4) ) = 646646 - (26208+1820) = 618618 or in scientific: 6.19x10^5 (but why ...
February 18, 2016

Math
multiply each term by 5x, the LCD 10 - x^2 = x -x^2 - x + 10 = 0 x^2 + x - 10 = 0 x = (-1 ± √41)/2 --> exact answer, or = appr 2.702 or -3.702
February 18, 2016

Math
Surely you can do better than 3.1 for π Calculators have π built-in with about 10 decimal place accuracy. area of mat = 25π m^2 cost per m^2 = 15.5/(25π) dollars/m^2 = .197.. or 20 cents/m^2 You found how many m^2 we can get for $1.00
February 18, 2016

Math
Peter' age --- x Veronica ---- x+2 x + x+2 = 24 take over
February 18, 2016

northdale middle school
looks like they are charging $9 per hour so Cost = 9t, where t is in hours
February 18, 2016

math
first term -- a term3 = a + 2d, but term3 = 4a 4a = a+2d 3a = 2d term6 = a + 5d = 17 or a = 17-5d sub that into 3a = 2d 3(17-5d) = 2d 51 - 15d = 2d 51 = 17d d = 3 then 3a = 6 a = 2 terms are: 2, 5, 8, 11, 14, 17 , all checks out, the fourth terms is 4 times the first and the ...
February 18, 2016

PreCalc
look back at your earlier post of this question.
February 18, 2016

math
width --- x length --- x+7 2x + 2(x+7) = 62 solve for x
February 18, 2016

maths-probability
to get 4: 1,3 2,2 3,1 --- there are 3 cases prob(4) = 3/36 = 1/12
February 18, 2016

Geometry
agree
February 18, 2016

Math
area of triangle = (1/2)(base)(height) 110 = (1/2)(10)height 110 = 5height height = 110/5 = 22
February 18, 2016

Math
extra games to win --- x (6+x)/4 = 2/1 6+x = 8 x = 2 they must win 2 more games or, by common sense .... the lost 4, to have 2:1 win:loss ratio, they must win 8 already won 6, so they must win 2 more.
February 18, 2016

precalc
So we have f(x) = √(x+3) and I bet it is also : (f(a+h)−f(a))/h (f(a+h)−f(a))/h = ( √(a+h + 3) - √(a+3) )/h = ( √(a+h + 3) - √(a+3) )/h * (√(a+h + 3) + √(a+3) ) / (√(a+h + 3) + √(a+3) ) = (a+h+3 - a-3)/( h(&#...
February 18, 2016

Maths
Are we counting either 1 or the number itself as factors e.g. - are the factors of 10 just 2,5 or 1,2,5,10 ?
February 18, 2016

MATH
looks like the recipe is tripled (from 8 to 24) so let' triple the milk 3(7/4) = 21/4 or 5 1/4 cups of milk or 3(1.75) = 5.25
February 18, 2016

college loan
300( 1 - 1.0041666^-n)/.0041666...) = 10000 1 - 1.00416666^-n = .138888866.. 1.00416666..^-n = .861111133 take log of both sides: -n log 1.0041666.. = log .861111133.. -n = -35.96 n = appr 36 so it would take 36 months or 3 years
February 18, 2016

Calculus
Because of the nice symmetry (and the x-intercepts -1 and +1) area = 2 ∫(1 - x^2) dx from 0 to 1 which matches the last choice
February 18, 2016

Calculus
I could easily integrate #1 and #4 I see no difference isn #2 and #3, but would have difficulty with that one.
February 18, 2016

Calculus
take a look at this http://mathhelpboards.com/questions-other-sites-52/leprofeces-question-yahoo-answers-minimizing-lateral-area-cone-fixed-volume-8554.html
February 18, 2016

Math
check your typing. if the 15 inches is the diameter, then the radius is 7.5 if the 15 inches is the circumference, then the radius is appr 2.38, which is not one of the choices.
February 18, 2016

PreCalc
zeros −3, 0, 1, 4 -->x(x+3)(x-1)(x-4) expanding this gives us x^4 - 2x^3 - 11x^2 + 12x but we are told that the x^3 terms is 4x^3 and we have it as -2x^3 so there had to be a -2 in front of the whole mess polynomial is -2x(x-1)(x-4)(x+3) or -2x^4 + 4x^3 + 22x^2 - 24x
February 17, 2016

COLLEGE
(-4)^2 + 5 = 16=5 = 21 but ... -4^2 + 5 = -16 + 5 = -11
February 17, 2016

math
the quotient of -128 and 8 is -16 so 13 - (-16) = 29
February 17, 2016

Calculus HELP TEST TOMMOROW
when t = 0, s = 0 when t = 5 , s = 3(25) = 75 b) when t = 10 , s = 300 rate = (300-0)/(10-0) = 30 m/s c) v(t) = 6t when t = 10, v(10) = 60 m/s d) 3t^2 = 600 t^2 = 200 t = √200 = appr 14.1 seconds
February 17, 2016

Algebra
the lead term is -3x^5 , which on the graph would drop down rapidly into the fourth quadrant when x gets larger.
February 17, 2016

Calc
do you mean √(5+4t^2) ? - nothing to simlify do you mean √5 + 4t^2 ? - nothing to simplify
February 17, 2016

Antidifferentiation
we know a = -9.8 v = -9.8t + c when t = 0 , v = 8 8 = 0+c --> c = 8 v = -9/8t + 8 s = -4.9t^2 + 8t + 63 , where s is the distance in metres. at hitting the ground, s = 0 -4.9t^2 + 8t + 63 = 0 t = (-8 ± √1298.8)/-9.8 = appr 4.49 seconds or a negative t
February 17, 2016

math
assuming that the head size is a function of the head's circumference, treat it as having two ordered pairs (21.5,6.875) and ( 21.875,7) -- >(c,h) "slope" = (6.875-7)/(21.5 - 21.875) = 1/3 using the point( 21.5, 6.875) h = 1/3c + b 6.875 = 1/3(21.5) + b b = -....
February 17, 2016

Algebra
Assuming you meant: √7 x(√x - 7√7) = x√(7x) - 49x brackets are important here e.g √(7x) vs √7x , the last one is (√7)x
February 17, 2016

Math
Unless somebody made a calculation error, they will obtain the same answer, since for a straight line, the slope is always the same, no matter where you take the slope.
February 17, 2016

Algebra
Alexa, I answered this for you yesterday http://www.jiskha.com/display.cgi?id=1455679992 Your expansion is correct, but as I stated yesterday , why not just leave the answer as Volume = (5a+4b)^3 For any given value of a and b, it would be so much easier to find the volume ...
February 17, 2016

math plz help !!!
prob of J = 1/8 so prob of NOT J = 7/8 so what do you think?
February 17, 2016

Math
(3x)(3x)(3x)(3x) = 81x^4
February 17, 2016

Math-Algebra
correct
February 17, 2016

Geometry
correct
February 17, 2016

math - probability
The coin flip was a prob of 1/2 so (1/2)(x) = 12/40) x = 24/40 = 12/20, I wanted 20 at the bottom since there are 20 marbles so something 12 out of 20 ?? how about 3 white or 9 blacks Pierre's question: What is the probability of head and not a green marble, or What is the...
February 17, 2016

Algebra
so you are looking for ae^-0.0358t = .5a e^-0.0358t = .5 take ln of both sides, and recall ln e = 1 -.0358t = ln .5 t = ln .5/-.0358 = .....
February 17, 2016

Algebra 2
100(.92)^t = 62 .92^t = .62 logs ... t log.92 =log .62 t = 5.7 years Make the necessary proper statements.
February 17, 2016

maths
the area of a rhombus = (1/2) product of its diagonals let d be the other diagonal (1/2)(19.2)d = 148.8 you do the arithmetic
February 17, 2016

Math
67(1/2)^(t/124) = 18 or .5^(t/124) = .2686.. take log of both sides (t/124)log .5 = log .2686.. t/124 = 1.896164... t = appr 235 years check: after 124 years, there would be 33.5 g left after 248 years , there would be 16.75 g My answer is reasonable
February 17, 2016

math age problem
(1/2)S + 2 = 12 solve for S
February 17, 2016

maths
missing data
February 17, 2016

Trig
water ? let the distance from the point of attachment to the ground be h sin52° = h/12 h = 12sin52 = ... add 10.5 to h to get the height of the pole
February 17, 2016

math
smaller --- x larger ---- 2x+10 x + 2x+10 = 43 solve for x
February 17, 2016

Algebra
yes, your last one of $27,099 is correct
February 17, 2016

Algebra
x(1.07)^16 = 80000 solve for x, the original value
February 17, 2016

algebra
I would have accepted the answer as : volume = (5a + 4b)^3 in your expansion , the last term in the last line should be 64b^3, you had 54b^2, probably just a typo since the previous line was ok.
February 16, 2016

Algebra
you are correct
February 16, 2016

math
I bet you, that second equation is y = 4-t^2 form the first: x^2 = 16t^2 --> t^2 = x^2/16 from the 2nd: t^2 = 4 - y so x^2/16 = 4-y x^2 = 64 - 16y , which is a parabola opening downwards. derivative: 2x = -16 dy/dx dy/dx = -x/8 x-intercepts of the parabola, let y = 0 x = &...
February 16, 2016

math
let the number of boys be 5x and the number of girls be 3x total students = 8x students in 1st class = .2(5x) + .6(3) = 2.8x percentage in 1st class = 2.8x/(8x) = 28/80 = .35 or 35%
February 16, 2016

PreCalc
let the dimensions be l, w, and 6 ft surface area = 2lw + 12l + 12w = 40 lw + 6l + 6w = 20 l(w+ 6) = 20-6w l = (20-6w)/(w+6)
February 16, 2016

PreCalc
each side will be x/3 inches sketch a height to create a 30-60-90° triangle let the height be h by ratios: h/(x/3) = √3/2 h = (x/3)(√3/2) = (√3/6)x area = (1/2)(base)(height) = (1/2)(x/3)(√3/6)x = (√3/36)x^2 check my arithmetic or h/(x/3) = ...
February 16, 2016

Math
Kathy's age now ---- x her age 3 years ago -- x-3 her age 4 years from now -- x+4 (1/2)(x-3) = (1/3)(x+4) times 6 3(x-3) = 2(x+4) finish it up
February 16, 2016

Math
x+y = 31 ---> y = 31-x xy = 140 x(31-x) = 140 31x - x^2 - 140 = 0 x^2 - 31x + 140 = 0 x = (31 ± √401)/2 = appr 25.512.. or 5.4875.. then y = 5.4875 or 25.512 the two numbers are (31+√401)/2 and (31-√401)/2
February 16, 2016

MATH HELP
f(x) = 5x^2 − 70x + 258 = 5(x^2 - 14x + 49-49) + 258 = 5(x-7)^2 - 245 + 258 = 5(x-7)^2 + 13 my choice is a) The minimum cost is 13, obtained when x = 7
February 16, 2016

Algebra
expensive tickets --- x cheap tickets ------ 3x+5 3.5x + 1.5(3x+5) = 1607.5 solve for x
February 16, 2016

math
Your decimals are not correct 0.5444444444 = .5 + .04 + .004 + .0004 + ... let's leave the .5 sitting aside for the time being. so we have .04 + .004 + ... a = .04, r = .1 sum of all = a/(1-r) = .04/(1-.1) = .04/.9 = 4/90 = 2/45 now bring in the .5 or 1/2 so 0,5444444444...
February 16, 2016

Maths
x + 10x + 100x = 1000 111x = 1000 x = 9 So by your "subtraction" after first jump : 1000-9 = 991 after 2nd jump : 991-90 = 901 after 3rd jump : 901-900 = 1 looks like he didn't quite make it.
February 16, 2016

Precal
use a ratio, C/360 = 140/210 C = 360(140/210) = ...
February 16, 2016

MATH HELP
The first part of the question is irrelevant. all we need is to compare 3.76% compounded monthly with 3.5% compounded daily let the first rate be i 1+i = (1 + .0376/12)^12 = 1.038254.. i = appr 3.825% let the second rate be j 1+j = (1 + .035/365)^365 = 1.0356.. = appr 3.56% ...
February 16, 2016

math
ar^4 = 360, but = 90 so .....
February 16, 2016

MATH HELP
credit union investment = 15000(1 + .05/365)^365 = $15,769.01 silver screen account = 20000(1 + .0525/12)^12 = 21,075.64 total after 1 year = 36,844.65 on an investment of 35,000 To make any comparison, we have to evaluate at the same "time spot". thus a) is not a ...
February 16, 2016

Trig identity inverses
go with Steve's answer, I forgot that we could pin-point the quadrant (although mine had the more-fun calculations)
February 16, 2016

Trig identity inverses
cos[cot^-1 (-√3) + sin^-1 (-1/2)] let's take it in parts cot^-1 (-√3) is the angle so that cotØ = -√3 or tanØ = -1/√3 I know tan30° = +1/√3 so Ø = 180-30 = 150° or -30° (usually we take the smallest positive ...
February 16, 2016

Quick calc question
since lnx is defined only for x > 0 it's integral can be defined only for x>0 You figure out which of the choices matches that, I love and prefer the good ol' way of expressing relationships like that.
February 16, 2016

Quick calc question
∫1/x dx from 1 to 2 = lnx | from 1 to 2 = ln2 - ln1 = ln2 , since ln1 = 0
February 16, 2016

geometry please help!
#1 your function is a parabola #2. y=5-2/3x -- linear, if you mean 5 - (2/3)x y=5x^2+7 -- obviously non-linear y=1.5x-0.25 y=3 y=10/x+20 --- non-linear #3 y=3/4x-7/8 --> a straight line if you mean (3/4)x - 7/8 a curve if you mean 3/(4x) - 7/8
February 16, 2016

Math
c = √(76.4^2 + 39.3^2) = ...
February 16, 2016

maths
clearly you will have to cut some of the 4x8's If we place the long side of the 4x8 along the long side of the floor, we will need 3 sheets, with some cut off. We will then have the 4 ft part along the 13 ft part of the floor, needing 4 sheets with lots of waste. This &...
February 16, 2016

math
If the time is the same, and the rate is the same, the area of the two fields must be equal so (40)(w) = 20^2 w = 400/40 = 10 A farm which is 10 m wide ? mmmhhh....
February 16, 2016

MATH
If I understand the definitions correctly, "surface area" would be the total of all the areas of an object, while "lateral" surface area would exclude the base so the surface area of a square pyramid = area of the square base + 4(area of the triangle) That...
February 16, 2016

algebra
speed on first trip --- x km/h speed on return trip -- x+2 km/h recall that time = distance/rate difference in their times = 2 hrs ----> 240/x - 240/(x+20) = 2 everybody times x(x+20) 240(x+20) - 240x = 2x(x+20) 240x + 4800 - 240x = 2x^2 + 40x x^2 + 20x - 2400 = 0 (x-40)(x...
February 16, 2016

occupation
According to "Weigh-Watchers" tables, most herbs have no points.
February 16, 2016

math
correct
February 16, 2016

math
on the same grid, graph both y = x, which is a straight line, with slope 1 y = sinx http://www.wolframalpha.com/input/?i=plot+y+%3D+x,+y+%3D+sinx What do you notice? Where do they intersect ? slope of y = sinx = dy/dx = cosx when x = 0, cos0 = 1 for any value of -π/2 <...
February 15, 2016

Math
t = k/r, where k is a constant given: t = 5, r = 60 5 = k/60 k = 300 t = 300/r when r = 40 t = 300/40 = 7.5 hrs
February 15, 2016

math
Now: Jared --- x Eric ---- 2x 10 years ago: Jared --- x - 10 Eric -----2x-10 x-10 + 2x-10 = 19 solve for x
February 15, 2016

Math: Angles of Elevation and Depression
Once you make your sketch it is easy to see that tan40 = h/30 solve for h, the height of the pole
February 15, 2016

Math
so x+y=2 and xy=2 from the first: y = 2-x into the 2nd x(2-x) = 2 2x - x^2 - 2 = 0 x^2 - 2x + 2 = 0 solving by completing the square: x^2 - 2x = -2 x^2 - 2x + 1 = -2+1 (x-1)^2 = -i x-1 = ± √-1 = ± i x = 1 ± i
February 15, 2016

Math
x = (-√2 ± √(2 - 4(1)(1/2)) )/2 = - √2/2 ahh, then it must have factored sure enough (x + √2/2)^2 = 0 x = -√2/2 no need for complex numbers, the root is real.
February 15, 2016

math
your post is riddled with confusion is that log5 4 ?? what about the log5 -2x ? - is that log5 (-2x) ? and the log31, is that base 10 ? Normally when we don't state a base, it is understood to be 10
February 15, 2016

math
since he want to have 100,000 "forever" he will need a fund so that 6% of it = 100000 .06x = 100000 x = 1,666.666.67 so he has to accululate that much in 30 years, let the annual amount to save be P P(1.06^30 - 1)/.06 = 1,666,666.67 P = 21,081.15 is needed each year
February 15, 2016

math
what is 5700(1.0275)^12 ?
February 15, 2016

math
number of 25 rupees tickets ---x number of 30 rupees tickets --- 40-x 25x + 30(40-x) = 1125 solve for x #2 John ---x Babita -- 3x Ahmed ---5(3x) = 15x so ......
February 15, 2016

8th grade math - Variations
#1, good #2. yes #3. yes #4. yes in #3, and #4 aren't you supposed to write the equation? y = 3.5x , where x is in hours, and y is miles and d = 6.2t , where t is in hours and d in miles
February 15, 2016

Math
perfectly suitable for your question: http://davidmlane.com/hyperstat/z_table.html best on the web for stats
February 15, 2016

Math
show me your steps, it only takes 2 lines
February 15, 2016

Math
Just translate the English into Math "the length of the sides of each pen if the sides of the triangular pen are 16 less than twice a side of the square Pen." if side of square is x side of triangular pen is 2x-16 perimeter of square --- 4x perimeter of triangle -- 3...
February 15, 2016

Math
number of student tickets --- x number of guest tickets ----- 400-x solve for x 40x + 60(400-x) = 18500
February 15, 2016

Math College Algebra
No you can't use the formula for #1 If a = 0 , as it would be for the missing x^2 term, in the formula we are dividing by 2a and since we can't divide by zero, any results would be totally meaningless. So when "they" told you it could be done, tell "them...
February 15, 2016

Math College Algebra
re your question about the 13/12 in completing the square, the first thing you do is divide each term by the coefficient of the square term so you have x^2 in front - then take half of the middle term coefficient: 1/2 of 13/6 is 13/12 now square that and add to both sides (13/...
February 15, 2016

Math College Algebra
no, you can't do any of that. Since the 3 methods apply to quadratics and you don't have a quadratic in #1, the question is bogus. (That's like asking for 3 ways to bring a sailboat into a dock, when you sitting on a bicycle. )
February 15, 2016

Math College Algebra
first of all, the #1 is a linear function So the three methods you are asked to use apply to a quadratic function. So either silly or a typo. I will do the hard one, you must be able to do the other. -6x^2 - 13x + 5 = 0 6x^2 + 13x - 5 = 0 check if it factors: 6*(-5) = -30 does...
February 15, 2016

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