Wednesday

March 4, 2015

March 4, 2015

Total # Posts: 29,207

**Math**

for any parabola of the form y = a(x-h)^2 + k , the vertex is (h,k) and the axis of symmetry is x = h so in your case ......
*November 5, 2014*

**math**

it should not be too hard to actually list them Q-D-N 0 0 6 0 1 4 0 2 2 0 3 0 1 0 5
*November 5, 2014*

**Finance**

what is 1000(1.07)^20 ?
*November 5, 2014*

**trigo**

distance covered by both wheels must be the same ... with radians, arclength is simply rØ so 24Ø = 60(12) Ø = 30 radians
*November 5, 2014*

**Algebra**

Don't know what you want to "solve" You have a cubic function, are you graphing it? are you finding intercepts? ??
*November 5, 2014*

**Probability**

prob(right) = 1/4 prob(wrong) = 3/4 if passing grade is 8/10, then I will pass if I get 8/10 or 9/10 or 10/10 prob of that = C(10,8)(1/4)^8 (3/4)^2 + C(10,9)(1/4)^9 (3/4) + (1/4)^10 = appr .00041 check my arithmetic
*November 5, 2014*

**college statistics**

C(12,3) = 12!/(3!9!) = 220 Added attraction: Google Pascal's triangle look at the row: 1 12 66 220 495 .... here is a good one.. http://ptri1.tripod.com/
*November 5, 2014*

**algebra**

Your answers make no sense to me. How did you get these?
*November 4, 2014*

**algera**

find the derivative, set it equal to zero and solve.
*November 4, 2014*

**algebra**

You left your answer choices blank. What did you get?
*November 4, 2014*

**Calculus**

BUT, the given point is not on the curve, so what you did is bogus. look at your sketch, the point (0,-4) is below the parabola. Draw the two tangents, you will see that it touches the curve at two different points, one in the first quad, the other in the 2nd quad. Let the ...
*November 4, 2014*

**Calculus**

y' = 18x^2 + 5 we want 18x^2 + 5 = 4 18x^2 = -1 x^2 = -1/18 but that is not possible since the square of anything has to be positive, so there is value of x making this equations true thus there is not slope of 4 thuse there is no such tangent
*November 4, 2014*

**Calculus**

dy/dx = 6x^2 - 6x - 6 = 0 for a horizontal slope x^2 - x - 1 = 0 x = (1 ± √5)/2 = appr 1.618 or -.618 you are correct, but all it asked for is the values of x (did you know that the first answer x = 1.618.. is the "golden ratio " ? )
*November 4, 2014*

**Calculus**

correct
*November 4, 2014*

**math**

look at one of the 6 congruent triangles the base of it must be 78/6 = 13 area of one of them = (1/2)base x height = (1/2)(13)(11) = 143/2 square inches so the whole hexagon is 6(143/2) = 429 inches^2
*November 4, 2014*

**math**

adults --- x children --- 3x 7x + 3(3x) = 6000 16x = 6000 x = 375 so 375 adults and 1125 kids for a total of 1500 sold
*November 4, 2014*

**Math**

cost per quart for orange --- x cost per quart for grapejuice -- x-1 (5/2)(x-1) + (3/2)x = 12.5 times 2 5(x-1) + 3x = 25 8x = 30 x = 3.75 x-1 = 2.75 orange juice costs $3.75 per quart and grape juice costs $2.75 per quart
*November 4, 2014*

**math**

I am 100% sure it was measured in feet. Looks like Sandy is a kid or a short junior. The stick should come to your chin with skates on, and to about your nose without skates on.
*November 4, 2014*

**algebra**

number of dimes --- x number of nickels --- 2x 10x + 5(2x) = 120 20x = 120 x = 6 So 6 dimes and 12 nickels
*November 4, 2014*

**Algebra**

I have a feeling you meant f(x) = (x+5)/3 or is it the way you typed it ? confirm please
*November 4, 2014*

**math**

looks like plain ol' Pythagoras to me y^2 + 2.8^2 = 10.5^2 y^2 = 102.41 y = √102.41 = appr 10.12 m
*November 4, 2014*

**Algebra please help**

since a 2 ounce bag is 1/3 of a 6 ounce bag, I predict it will cost one third of $3.60.
*November 4, 2014*

**Algebra please help answer**

clearly 9:6 ≠ 4:3
*November 4, 2014*

**algebra**

I am assuming that the 2nd shift follows the first shift now: let the number of girls in A be x let the number of girls in B be y after 1st shift: A has x-7 B has y+7 "the number of girls in the classes would interchange" ---> y+7 = x 2nd shift A has x-7 + 4 = x-3...
*November 4, 2014*

**Algebra**

Are you sure you don't have any more information, such as an angle ? otherwise, let the third side be y P = 2(3x+2) + y
*November 3, 2014*

**Math: permutation**

let's choose the consonants and vowels first No of combinations = C(5,2) x C(2,1) = 10(2) = 20 Since you titled your post "permutations" we now want to arrange these. That can be done in 6 ways each So the number of permutations is 6(20) = 120
*November 3, 2014*

**Math**

looks like you are studying the binomial theorem You MUST memorize some basic formulas e.g. for (a+b)^n term(r+1) = C(n,r) (a^r)(b^(n-r)) so for (3x+9)^9 term6 = C(9,5)(3x)^5 y^4 = 126(243x^5)y^4 = 30618 x^5 y^4 b) what is the middle term for (3x + y^3)^8 ? c) let that term be...
*November 2, 2014*

**Math**

2.25 = 1(10^8) 1.5^(t/20) since the time would be same for a small country or a large country to increase by 124%, we can ignore the 10^8 take log of both sides log 2.25 = l log 1.5^(t/20 log 2.25 = (t/20) log 1.5 log2.25/log 1.5 = t/20 t = 20(log2.25)/log 1.5 = 40 years 2 = 1...
*November 2, 2014*

**Algebra**

Wow, that is the second post in a row that your re-posted before checking if your first posting had been anwered. http://www.jiskha.com/display.cgi?id=1414981217
*November 2, 2014*

**Algebra**

Bob did this for you Did you not check back ???
*November 2, 2014*

**Math**

from max to min = 254-88 = 166 so amplitude = 84 period = 20 min period = 2π/k 20 = 2π/k k = π/10 let p(t) = 83 cos π/10(t + d) + 171 when t = 0 we want p(0) = 88 88 = 83cos (π/10)cos(0 + d) + 171 -1 = cos (dπ/10) I know cos π = -1 so dπ...
*November 2, 2014*

**Pre-Calc**

draw a line from his final position to the centre and complete the triangle all the way around is 2πr = 6π so completed 6/6π or 1/π around the circle angle" Ø/360 = 6/6π Ø = 360/π = 114.59156° cosØ = x/3 and sin&...
*November 2, 2014*

**Math Calc**

I will assume that neither A nor B are the right angle, or else why would you ask to find it So tanB = 13/26 = 1/2 angle B = 26.565 then angle A = 63.435° (90 - B) c^2 = a^2 + b^2 = ... you finish it
*November 2, 2014*

**Algebra**

You probably meant: f(x) = (2x-1)/(x+5) I will assume that then y = (2x-1)/(x+5) we form the inverse by interchanging x and y x = (2y-1)/(y+5) xy + 5x = 2y -1 now solve this for y xy - 2y = -5x - 1 y(x-2) = -5x - 1 y = f^-1 (x) = (-5x - 1)/(x - 2) so by comparison, a = -5 b...
*November 2, 2014*

**Math**

We "solve" equations, yours is not an equation. Did you perhaps want to factor it ?? x^2 - (y^2 + 2y + 1) = x^2 - (y+1)^2 ahhh, a difference of squares ... = (x+y+1)(y-y-1)
*November 2, 2014*

**Algebra**

((7-10)+3)-5 ---> (10-7) + 3) - 5) = (-3+3) - 5 ----> (3-(-3)) - 5 = 6-5 ----------> 5-6 = -1
*November 2, 2014*

**Algebra (1)**

Is that (y+2)/(y+7) = 11/31 ?? , (looks like ll instead of 11) Are you solving for y ?? if so, just cross-multiply 31y + 62 = 11y + 77 20y = 15 y = 15/20 = 3/4
*November 2, 2014*

**Calculus**

when x = 3 f(3) = 1.201 , correct to 3 decimals so the point of contact is (3, 1.201) f ' (x) = e^(-.4x) (1/x) + (-.4) e^(-.4x) ln(18x) f ' (3) = -.380 correct to 3 decimals y - 1.201 = -.38(x-3) y = -.38x + 2.342 better check my arithmetic and button-pushing
*November 2, 2014*

**statistics and probability**

fewer than 4 defective ---> 0 ,1,2, or 3 are defective prob(defective) = 5/100 = 1/20 prob(not defective) = 19/20 prob = C(100,0) (1/20)^0 (19/20)^100 + C(100,1)(1/20)(19/20^99 + C(100,2)(1/20)^2 (19/20)^98 + C(100,3)(1/20)^3 (19/20)^97 = .00592.. + .03116.. + .08118...+ ....
*November 2, 2014*

**math**

4(x+15) ≥ 120 4x + 60 ≥ 120 4x ≥ 60 x ≥ 15
*November 2, 2014*

**Algebra**

let n be the number of pages scanned .02n + 70 ≤ .09n 70≤ .02n or .02n ≥ 70 n ≥ 3500 so 3500 pages is the break-even point so anything greater than 3500 she should rent the scanner, at less than 3500 her old scanner will be better.
*November 2, 2014*

**calculus**

arrrgggghhh! Wolfram says: http://integrals.wolfram.com/index.jsp?expr=x%5E2%2F%28%28x%2B3%29%283x%2B4%29%5E%281%2F2%29%29&random=false
*November 2, 2014*

**mathzzzz gkpp**

x(1.1)^2 = 12000 x = 12000/1.1^2 = appr 9917.36
*November 2, 2014*

**math**

Please use proper English with correct grammar and punctuation in your post. It would make it so much easier to establish what your are trying to say. Furthermore, is there a question such as, "Find x" ? sum of 8 number is x so the average of those 8 numbers is x/8 ...
*November 2, 2014*

**Intermediate Algebra**

I assumed that you meant (-9)^(1/2) which is the same as √-9 , which of course is not real vs -(9^(1/2)) which is -√9 which is -3 the ^ is the generally accepted symbol to indicate an exponent, e.g. x^2 is x squared, x^5 is x to the fifth, etc
*November 2, 2014*

**Intermediate Algebra**

This only makes sense if you meant √(-9) vs - (√9) remember we cannot take the square root of a negative number, that would be an imaginary or complex answer. but by the order of operation for -√9 we take the square root first, and then make the answer ...
*November 2, 2014*

**Solid Mensuration**

Remember that in a cyclic quadrilateral, the diagonal subtends a 90° angle. Since the two diagonals also intersect at 90°, the shorter diagonal must be bisected by the diameter. In my diagram, I labeled the diameter A and B and the point on the circle above AB as C My ...
*November 2, 2014*

**Calculs I**

btw, jorge's answer is bogus. I got 27203
*November 2, 2014*

**Calculs I**

y(t) = a e^(kt) , where a is the intitial count, and k is a constant, and t is in minutes You have two ordered pairs, (15,16000) and (45,22000) for (15,16000) 16000 = a e(15k) for (45,22000) 22000 = a e^(45k) divide the 2nd by the 1st 1.375 =e^(30k) ln both sides , that is : (...
*November 2, 2014*

**Calculus**

k(t)=(t^2-4)^2 = (t^2 - 4)(t^2 - 4) now do as instructed
*November 2, 2014*

**Calculus**

let the time after their split be t hrs I see a triangle with sides 10t and 6t and an angle of 120° between them let the distance between them be d miles by the cosine law: d^2 = (6t)^2 + (10t)^2 - 2(6t)(10t)cos120° = 136t^2 + 60t^2 d2 = 196t^2 d = 14t dd/dt = 14 mph...
*November 2, 2014*

**Calculus**

2x dx/dt + x dy/dt + y dx/dt + 2y dy/dt = 0 (dy/dt)(x + 2y) = -2x dx/dt - y dx/dt dy/dt(2 + 6) = -4(3) - 3(3) dy/dt = -21/8 the ant is moving DOWN at 21/8 cm/s
*November 2, 2014*

**Calculus**

C = 2πr dC/dt = 2π dr/dt A = πr^2 dr/dt dA = 2πr dr/dt you have the values to plug in for both rates.
*November 2, 2014*

**Calculus**

dV/dt = πr^2 dh/dt + 2πrh dr/dt plug in the given values SA = 2πrh , are you not considering the ends ? differentiate with respect to t using the product rule like I did for the volume, then plug in the values
*November 2, 2014*

**Calculus**

let the length be x inches let the width by y inches A = xy dA/dt = x dy/dt + y dx/dt for the given data... dA/dt = 24(-3) + 15(4) = -12 inches^2/min the area is decreasing at 12 square inches/min P = 2x + 2y dP/dt = 2 dx/dt + 2 dy/dt = 2(-3) + 2(4) = 2 inches/min
*November 2, 2014*

**Math**

i = .049/12 = .00408333... n= 15(12) = 180 amount = 10000(1.00408333..)^180 = $ 20,823.63
*November 2, 2014*

**Algebra**

notice that for every increase of 1 in the x, the y increases by 2 so slope = 2 or, more formally, take the fist two points (1,1) and (2,3) slope = (3-1)/(2-1) = 2 so y = 2x + b sub in the first point (1,1) 1 = 2(1) + b b = -1 y = 2x - 1 check the remaining points to make they...
*November 1, 2014*

**Algebra**

I assume you want it 'simplified' and that you forgot the brackets (8-6i)/(3i) = (8-6i)/(3i) * i/i = (8i - 6i^2)/(3i^2) = (6 + 8i)/-3 or =( -6 - 8i)/3 hint for the second... multiply top and bottom by (4-2i)/(4-2i)
*November 1, 2014*

**Math**

simply solve ... .07x + .15(x+1500) = 1545 where x is the amount invested at 7%
*November 1, 2014*

**Maths**

Please type your question in proper English. "d" is the common variable for the difference between consecutive terms of an AP and not as a substitute for "the".
*November 1, 2014*

**math**

Finding the distance between 2 points and finding the midpoint between 2 points should be part of your repertoire of common and memory-recall-ready formulas if you want to study math for (a,b) and (c,d) Distance = √( (c-a)^2 + (d-b)^2 ) midpoint = ( (a+c)/2 , (b+d)/2 ) ...
*November 1, 2014*

**Algebra**

so a#b =(a+b)/2 then ((1#2)#2)#4 = (1.5#2)#4 = 1.75#4 = 2.875 or = 23/8 or ((1#2)#2)#4 = (3/2#2)#4 = (7/4)#4 = 23/8
*November 1, 2014*

**Algebra**

P(g(x)) = p(4-3x) = 4 + 2√(4 - 3x + 2) = 4 + 2√(6-3x) remember we cannot take the square root of a negative, so 6-3x≥0 -3x ≥ -6 x ≤ 2 so the largest value of a is 2
*November 1, 2014*

**MATHS**

I will need 2 zeros (0 can't be in front) 3 ones 3 twos 3 fours ... 3 sevens 2 eights 2 nines total = 29 for b) we can save the 2 nines, (the 3 sixes will suffice) so they can save 2 cards
*November 1, 2014*

**Maths**

Prob(m) = 1/5 prob(S) = 4/5 Possible outcomes in best of three" MM --- (1/5)(1/5) = 1/25 MSM -- ((1/5)(4/5)(1/5) = 4/125 SMM -- ((4/5)(1/5)(1/5) = 4/125 SS ---- (4/5)(4/5) = 16/25 ----> Sue wins SMS -- (4/5)(1/5)(4/5) = 16/125 ----> Sue wins MSS -- ((1/5)(4/5)(4/5...
*November 1, 2014*

**Algebra**

πr^2 = 2πr r^2 - 2r = 0 r(r-2) = 0 r = 0 , the trivial answer or r = 2 So the diameter is 4 a/b = 2/3 or 2b = 3a, or b = 3a/2 (a+5)/b = 5/6 5b = 6a + 30 5(3a/2) = 6a + 30 times 2 15a = 12a + 60 a = 20 and b = 3(20)/2 = 30 the fraction was 20/30 y < √x by 4 y...
*October 31, 2014*

**Math**

factor is 10^8.8/10^7.1 = 10^1.7 = appr 50 times as strong
*October 31, 2014*

**Math**

number of quarters ---- x " he has one more dime than he has quarters" ---> dimes ---- x+1 now for the "value" of coins equation: 25x + 10(x+1) = 115 25x + 10x + 10 = 115 35x = 105 x = 3 etc
*October 31, 2014*

**Width of a square**

How can 45/10 = 3.5 ?? 45/10 = 4.5
*October 31, 2014*

**math**

You are looking for those values of x, so that y = (x+5)/(x-2) lies above the x-axis first of all, x ≠ 2 or else we are dividing by zero critical values are -5 and 2 investigate x < -5, say x = -10 then y = -/- = + , that's good investigate between -5 and 2, say x...
*October 31, 2014*

**maths**

I will assume you meant: 1/( (x+2)(x+3) ) - 1/( (x-4)(x-5) ) what about it? are you simplifying?
*October 31, 2014*

**Math, Can someone check my answers?**

all 3 are correct
*October 31, 2014*

**Thanks Steve - Pre Calculous**

for keeping an eye on me. I just have to read more carefully, I read it as sinx = 1/4
*October 31, 2014*

**Pre Calculous**

my keystrokes on my calculator: 2nd sin .25 = to get 14.478° but the sine is positive in I and II so x could also be 180 - 14.478 = 165.522° there are an infinite number of solutions, just add/subtract 360° to any existing answer to produce more.
*October 31, 2014*

**Math Calc**

divide by 7 sinØ = 6/7 Ø = arcsin (6/7) = appr 58.997° Did you use a calculator? my keystrokes: 6 ÷ 7 = 2nd sin = to get my answer
*October 31, 2014*

**Math Arc Length**

circumf = 2πr = 2π(4.9) = 9.8π so 360° of arc = 9.8π units and 1° of arc length = 9.8π/360 = 49π/1800 units Maybe they didn't like your decimal, but your answer is correct
*October 31, 2014*

**Calculus**

dy/dx = 4x + 5 dy = (4x + 5)dx so for your given data dy= (20+5)(.1) = 2.5 so the other one the same way
*October 31, 2014*

**math**

amount poured into canister --- x g amount in canister = 5026 + x amount left in bag = 4157-x g 5026+x = 2(4157-x) 5026 + x = 8314 -2x 3x = 3288 x = 1096 amount left in bag = 4157-1096 = 3061 g
*October 31, 2014*

**trigonometry**

LS = sinx(cos2x) + cosx(sin 2x) RS = sin(3x) = sin(2x + x) = (sin 2x)cosx + (cos 2x) sinx = LS I am using sin(A+B) = sinAcosB + cosAsinB
*October 31, 2014*

**Math Please Check**

you have found the variables which will yield the maximum and minimum , but you have not found the actual max or min When t = 0 (you had x = 0) h(0) = 0-0 = 0 when t = 2, h(2) = 8 - 12 = -4 also h(-1) = -1 - 3 = -4 so you have a local max at (0,0) and a local min at (2,-4) for...
*October 30, 2014*

**business maths**

I have no idea what your equation is supposed to say or do. Since you are talking about a "focal date", I will assume you have learned to make a time line. label it "now" or 0, 1,2,3 months I place the debt above the line , and the payments below the line, ...
*October 30, 2014*

**geometry**

not enough data all we know is that the total area of pool plus walkway is 72 units^2 so 9x8=72 , perimeter = 34 6x12 = 72 , perimeter = 36 4x18 , perimeter = 44 etc
*October 30, 2014*

**pre-algebra**

so the area of each of the smaller squares = 100/25 = 4 ft^2 so each side of the smaller square must be 2 ft
*October 30, 2014*

**can't figure it out**

Bob, looks like you missed that silly little negative sign in front of the 5 too, just like I did when I answered this question the first time for Ernie, John, and now Charlie . One would assume that he would check back to his previous post before posting the same question ...
*October 30, 2014*

**Math 11**

So you have a tetrahedron area of one of the triangles = (1/2)(16)(16)sin60 = 128(√3/2) = 64√3 Counting the base there are 4 faces, so surface area = 4(64√3) = 256√3 = appr 443.4 cm^2 If you don't want to count the base, multiply by 3 instead of by 4
*October 30, 2014*

**Math**

A two-term ratio can not be equal to a constant looks like a typo
*October 30, 2014*

**math really need help!**

done, look back
*October 30, 2014*

**oops math please help**

didn't notice that little - in front of the 5 f(x+2) = -5(x+2) + 6 you finish it this time
*October 30, 2014*

**math please help**

replace the x with x+2 f(x+2 = 5(x+2) + 6 = 5x + 16
*October 30, 2014*

**Math-urgent-**

huh? how many times are we to subtract ? on the other hand ... 11/12 ÷ 3/4 = (11/12)(4/3) = 44/36 = 11/9
*October 30, 2014*

**algebra**

times 2 14 + 6t = 6 - t 7t = -8 t = -8/7
*October 30, 2014*

**Math**

should have been y-1 = (1/4)(x-1) y = (1/4)x - 1/4 + 1 = (1/4)x + 3/4
*October 30, 2014*

**Algebra**

ahhh, your slope is not zero look at your 3/0 we CAN'T divide by zero , 3/0 is undefined If you look at your sketch , your line will be a vertical line Anytime you have a vertical line, your slope will be undefined and the equation will simply be x = some constant look at ...
*October 30, 2014*

**math**

c + 2s = 10.30 3c + 2s = 18 subtract them 2c = 7.7 c = 3.85 sub back into the first equation to get 3.85 + 2s = 10.3 2s = 6.45 s = 3.23 so c + s = 7.08
*October 30, 2014*

**Equation ratio**

if 5x = 4.5y then y/x = 5/4.5 = 10/9 y : x = 10 : 9
*October 30, 2014*

**Math**

7/3 = rear/2 3rear = 14 rear = 14/3 or 4 2/3 turns or 3 pedal turns = 7 rears 1 pedal turn = 7/3 rears 2 pedal turns = 14/3 rears
*October 29, 2014*

**Math**

yes (4/3)π r^3 = 1767.1 r^3 = 21.864.. r = 7.4999 or appr 7.5 m check: (4/3)π(7.5)^3 =1767.145..
*October 29, 2014*

**Math**

The least common multiply (LCM) of 12 and 20 is 60 So to make 60 burgers, we need 60/12 or 5 patty packages, and 60/20 or 3 bun packages.
*October 29, 2014*

**Math**

According to your equation, the object was 125 m above ground (t=0) , when it was shot solve for h = 0 , this will give you the two times it is on the ground -5t^2 + 120t + 125 = 0 divide by -5 t^2 - 24t - 25 = 0 (t-25)(t+1) = 0 t = -1 or t = 25 but, this only makes sense for ...
*October 29, 2014*

**Trigonometry**

2cosxcsc2x = cscx LS = 2cosx(1/sin 2x) = 2cosx(1/(2sinxcosx) = 1/sinx = csc x = RS sin^2 2x = 4 sin^2 x cos^2 x will use the same identity as in the first one: namely, sin 2x = 2sinxcosx LS = sin^2 2x = (sin 2x)(sin 2x) = (2sinxcosx)(2sinxcosx) = 4 sin^2 x cos^2 x = RS cot 2&...
*October 29, 2014*

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