Friday

January 20, 2017
Total # Posts: 37,332

**math**

I assume that you mean: "Luis rides his bicycle 3/4 of a mile in 5 minutes" Since 5 minutes is 1/12 of an hour, like you stated rate = distance/time = (3/4) / (1/12) mph = 9 mph

*November 7, 2016*

**pre-calc.**

ln(100) = ln(10^2) = 2ln10 so ln100/ln10 = 2ln10/ln10 = 2

*November 7, 2016*

**Pre-Calc**

cot x = 1/2 can be written in an infinite number of ways, the 1/2 is simply the ratio expressed in simplest form how about cot x = .5/1 or how about cotx = .378/.756 etc by definition cotx = adjacent side/opposite side in a right-angled triangle so in the original given cotx...

*November 7, 2016*

**Math**

x^2 + 2^2 = 5^2 solve for x

*November 7, 2016*

**If y= (2x + 2)^3 find dy/dx using chains rule**

I would just do it in one step dy/dx = 2(2x+3)^2 (2) = 4(2x+3)^2 using the steps asked for: let u = 2x+2 du/dx = 2 then y = u^3 dy/du = 3u^2 dy/dx = (dy/du)(du/dx) = (3u^2)(2) = 4u^2 = 4(2x+2)^2 Once you see the pattern of these type of derivatives, you should be able to ...

*November 7, 2016*

**Algebra 2**

two consecutive even integers ---> x and x+2 x + x+2 ? 130 2x ? 128 x ? 64 so how about 62 and 64 as the largest pair

*November 7, 2016*

**Math**

3 + 6*4 + 3

*November 7, 2016*

**Math**

I recognize this to be an circle. Do you want it in standard form? if so, then ... 8x+x^2-2y=64-y^2 x^2 + 8x + ... + y^2 - 2y + ... = 64 complete the square x^2 + 8x + 16 + y^2 - 2y + 1 = 64 + 16 + 1 (x + 4)^2 + (y-1)^2 = 81 centre is (-4,1), radius is 9

*November 7, 2016*

**Calculas**

Steve did this for you http://www.jiskha.com/display.cgi?id=1478532807 Why are you reposting?

*November 7, 2016*

**math**

the middle term of the expansion is term(10) term(10) = C(20,9)(1)^11 x^9 = 167960x^9 the 9th term is C(20,8) x^8 = 125970x^8 the 12 term is C(20,11) x^11 = 167960x^11 geometric mean = ?(125970(167960)x^19) 167960x^9 = ?(125970(167960)x^19) 167960x^9 = ?(125970(167960))*x^9 ?x...

*November 7, 2016*

**math**

Now: Patty ---- x years Sam ----- 4x next year: Patty = x+1 Sam = 4x + 1 4x+1 = 3(x+1) continue

*November 7, 2016*

**math**

lw = 24 2l + 2w = 20 l+w = 10 l = 10-w in lw = 24 (10-w)(w) = 24 10w - w^2 = 24 w^2 - 10w + 24 = 0 (w-6)(w-4) = 0 w = 6 , then l = 4 w = 4 , then l = 6

*November 7, 2016*

**Calculas**

nothing to see here

*November 7, 2016*

**math**

one angle ---- x the other ----- (2/3)x or 2x/3 2(x+2x/3) = 360 2x + 4x/3 = 360 carry on

*November 7, 2016*

**maths**

" ... the sum of the first five terms is one-fourth of the next terms." confusing, I will assume you meant: the sum of the first five terms is one-fourth of the next term. i.e. the sum of the first five terms is one-fourth of the 6th terms. a = 2 6th term = a+5d sum(...

*November 7, 2016*

**Math**

width ---- x length ---- 3x - 1 2x + 2(3x-1) = 40 carry on

*November 7, 2016*

**math**

(5/6)x + 3.60 = 4.35

*November 7, 2016*

**Finance**

i = .12 n = 50-18 = 32 amount = 1500( 1.12^32 - 1)/.01 = $457,271.58 where can you get 12% these days?

*November 7, 2016*

**trig help**

cosec40(sin40+sin80+cos120) = (1/sin40)(sin40 + sin80 + cos120) = 1 + sin80/sin40 + cos120/sin40 = 1 + 2sin40cos40/sin40 -1/(2sin40) = 1 + 2cos40 - (1/2)csc40

*November 7, 2016*

**algebra**

D^2 = 10^2 + 7^2 = 149 D = ?149 = appr 12 , to the nearest whole number

*November 7, 2016*

**maths**

width --- x length ---- 3x 2(x+3x) = 1.6 km 8x = 1600 m x = 200 then 3x = 600 The field is 200 m by 600 m for an area of 120,000 m^2

*November 7, 2016*

**@ Joshua - maths**

I also have seen this question now for the third time. I also keep ignoring it since it can't be answered with the information given. Include me in the "bad attitude" category.

*November 7, 2016*

**MATH**

what is 25000(1 + .0485/4)^24 ?

*November 6, 2016*

**Math**

yup, you are right. Need a third cup of coffee. I agree that the question makes no sense.

*November 6, 2016*

**Math**

The exterior angles of any polygon add up to 360° so: 3x+2x+4x = 360 x = 40

*November 6, 2016*

**Mathe**

I agree with appr 2.83 m but you would round that to 3 m , not 2 m since A and C have no units, I suspect a typo, and one of those was 3 m

*November 6, 2016*

**@ nms, Algrebra readiness**

It said " the negative square root of 7" ---> -?7 not " the square root of negative 7" ---> ?-7

*November 6, 2016*

**Algrebra readiness**

the negative square root of 7= appr -2.6 so to the nearest integer that would be -3 None of your choices given match that ???? #2 If each square is 2 by 2 ft, its area is 4 ft^2 and 30 of them would give us 120 ft^2 --> we need 170 If each square is 3 by 3 ft, its area is 9...

*November 6, 2016*

**maths**

Thanks nms for catching my error I used 2/3 instead of 1/3 (I must have looked back at the wrong fraction)

*November 6, 2016*

**maths**

rate of pipe A = 1/15 rate of pipe B = 1/10 combined rate = 1/6 amount done after 4 minutes = 4(1/6) = 2/3 so 1/3 is left to be done time using only A = (2/3) / (1/15) = 10 minutes

*November 6, 2016*

**Math-Trigo**

It said "without a calculator" All the work following is done in my head. sinA = -12/13 = y/r x^2 + y^2 = r^2 x^2 + (-12)^2 = 13^2 x^2 + 144 = 169 x^2 = 25 x = ± 5 , but A is in quad IV, so x = 5 so sinA = -12/13, cosA = +5/13 tanA = (-12/13) / (5/13) = -12/5 ...

*November 6, 2016*

**trig**

Did you make your sketch? On mine I let Jane's distance to the tower's base be x m, and Bill's distance to the tower be y m There are two right-angled triangles For Jane: tan70° = 34/x x = 34/tan70° do the same step for Bill's distance add x and y

*November 6, 2016*

**Maths**

My diagram: A vertical line PQ, to show the tower, P at ground-level Another vertical AB, the points of observation with A at ground-level let AP = x draw a horizontal from B to meet PQ at R in triangle APQ tan 60 = (h+40)/x x = (h+40)/tan60 in triangle BRQ tan30 = h/x x = h/...

*November 6, 2016*

**Calculus**

u • v = |u| |v|cosØ, where Ø is the angle between them -4 -21 = ?50 ?25 cosØ -25 = 25?2cosØ cosØ = -1/?2 Ø = 135°

*November 5, 2016*

**Pre-Calculus**

(u • v)(u + v) = (-4-21)(<3,4>) = -25<3,4> = <-75, -100>

*November 5, 2016*

**maths**

2x=3x subtract 2x from both sides 0 = x

*November 5, 2016*

**Algebra 2**

not familiar with your notation does log(30,8) mean log30 8 ?

*November 5, 2016*

**algebra**

V = kt/p for the given data: 20 = k(350)/35 k = 20(35)/350 = 2 V = 2t/p when t=330, p=30 V = 2(330)/30 = 22

*November 5, 2016*

**MATH**

"y varies inversely with x" ---> y = k(1/x) y = 8 when x = 5 8 = k/5 k = 40 so : y = 40/x plug in x=2, and find y

*November 5, 2016*

**Adv function**

I suspect a typo http://www.wolframalpha.com/input/?i=Cos%5E4(x)%2Bsin%5E4(4)%3Dcos(2x) notice the graph of the left side does not intersect the graph of the right side

*November 5, 2016*

**Algebra**

a) depends on how you define your variables e.g. let the time be t hours, and the distance be d miles then : d = kt plug in d= 180 and t = 4.5 to solve for k rewrite the equation , now that you know k sub in d = 320 and solve for t

*November 5, 2016*

**Mathe**

number of way to have a sum of 4: 13 22 31 number of ways to have a sum of 6: 15 24 33 42 51 prob(sum of 4 OR sum of 6) = 8/36 = 2/9

*November 5, 2016*

**Calculus**

Since you are in Calculus, I assume you know the area of a triangle is (1/2) ab sinØ, where Ø is the contained angle between a and b A = (1/2)(4)(4)sinØ A = 8sinØ dA/dØ = 8cosØ for a max of A, 8cosØ = 0 Ø = 90° or 270...

*November 5, 2016*

**Arithmetic**

add up the 3 costs, then divide by 3

*November 5, 2016*

**Arithmetic**

value of original stock = 75(50) = 3750 after increase of 8%, the value is 3750(1.08) = 4050 number of shares = 4050/50 = 81

*November 5, 2016*

**Math**

If I recall, a gross is defined to be 144 so they bought 6(144) or 864 pencils at a weekly use of 24 pencils, the number of weeks = 864/24 or 36

*November 5, 2016*

**math**

total profit = 6200-4000 = 2200 number of bikes at $50 profit per bike = 2200/50 = 44

*November 5, 2016*

**math**

done later this morning

*November 5, 2016*

**Algebra**

7?9 + 5(8-3) = 7(3) + 5(5) = 21 + 25 = 46

*November 4, 2016*

**tri**

make a sketch distance along first direction = 5 hrs x 23 knots = 115 n miles distance along 2nd direction = 6(23) = 138 n miles angle between the two directions = 150° by cosine law: x^2 = 115^2 + 138^2 - 2(115)(138)cos 150° = 59756.64... x = 244.45 nautical miles = ...

*November 4, 2016*

**Adv function**

"I can't get the l.s to equal r.s" If you are trying to show that it is an identity, good luck , since it is not (try it with 30° for x) So I will assume you are solving: (2-sin^2x)/-sinx=sinx 2 - sin^2 x = -sin^2 x 2 = 0 , which is a contradiction, there is ...

*November 4, 2016*

**math- Trigonometry**

I recognize .8641 as an approximation to ?3/2 if cos x = ?3/2 x = 30° sin30° = 1/2 or .5 using your .8641 sinx = .5033

*November 4, 2016*

**algebra 1**

or a line parallel to y = 5x - 2 is y = 5x + b , but (8,-2) lies on it -2 = 40 + b b = -42 y = 5x - 42

*November 4, 2016*

**geometry**

no idea where A, B, C, D, and O are Cannot be answered as is.

*November 4, 2016*

**Math**

selling price = .75(172.36) final price after tax = (1.09)(.75)(172.36) = ...

*November 4, 2016*

**Math**

Oh, dear, I think a ban for D&B is certainly due.

*November 4, 2016*

**Tricky Math Question**

0^0 is undefined reason: 0^n = 0 for any value of n but a^0 = 1 for any value of a so we have a contradiction, which drives mathematicians crazy, thus it is undefined my 25 year old calculator gives me an error message for 0^0

*November 4, 2016*

**Mathematics**

15 > 7 - t/3 The method for solving in-equations is the same as that for solving equation, except: when you multiply or divide by a negative number, you must reverse the inequality sign add t/3 to both sides t/3 + 15 > 7 subtract 15 from both sides t/3 > -8 multiply ...

*November 4, 2016*

**Math**

profit = 75 percentage profit = 75/300 = .25 or 25%

*November 4, 2016*

**Math**

Repost using proper English.

*November 4, 2016*

**@ anridas - Maths**

Please don't post a question as an answer to somebody else's posting. the square numbers less than 144 are 121, 100, 81, 64, 49, 36, 25, 16, 9, 4, 1 ... looks like 16 and 9 are it. since 16 x 9 = 144 or: 144 = 4 x 4 x 3 x 3 = 4^2 x 3^2 = 16(9)

*November 4, 2016*

**Maths**

since 1/10 + 2/3 + 1/7 < 1 , there have to be other colours, and yes, it is possible 1/10 + 2/3 + 1/7 = 191/210 minimum counters is 210 191/210 = x/1000 210x = 191000 x = 909.5 but we have to round down since we can't have partial counter, so 909 counters

*November 4, 2016*

**Math**

add: 2 1/5 + (1/2)(2 1/5) + (7/8)(2 1/5) = 11/5 + (1/2)(11/5) + (7/8)(11/5) = 11/5 + 11/10 + 77/40 take over, the LCD is 40

*November 4, 2016*

**Algebra**

let the certain amount of 8% stuff be x oz .5(8) + .08x = .32(8+x) solve for x

*November 4, 2016*

**mathematics**

poorly worded question. We only "solve" equations, you don't have an equation. I will assume you meant: m^2 + 6m + 7 = 0 m^2 + 6m + .... = -7 + ..... m^2 + 6m + 9 = -7 + 9 (m+3)^2 = 2 m+3 = ± ?2 m = -3 ± ?2

*November 4, 2016*

**Maths**

so .75x = 8400 x = 8400/.75 = .... "wold" ----> would

*November 4, 2016*

**Math**

Bar model??? standard way: Ryan ----- x cans Anne ----- x/2 cans Joel ------ 2x cans x + x/2 + 2x = 1925 (7/2)x = 1925 x = 550 take over

*November 4, 2016*

**Maths.**

You don't need a "×" symbol to show multiplication. Use brackets or * or standard algebraic notation e.g. 3×x^2×y ---> 3(x^2)(y) or simply 3x^2 y Furthermore, you will need brackets to eliminate any ambiguity I read yours as: 3x^2 y + (5/8)x^...

*November 4, 2016*

**math**

1800 mm = 180 cm = 1.8 m Consider 1 ha as 100 m by 100 m Assume the plough does swaths of 1.8 m up and down. 100/1.8 = 500/9 runs each 100 m long have to be ploughed total distance = (500/9)(100) m time = distance/rate = (500/9)(100) m / 7 km/h = (500/9)(100) m / 7000 m/h = ....

*November 4, 2016*

**Maths**

51 = 1+50 = 2 + 49 ... = 50+1 there are 50 such cases out of 50(50) so prob = 50/(50*50) = 1/50 55 , the smallest we can start with is 5 55 = 5 + 50 = 6 + 49 .. = 50 + 5 ----> 46 of them prob = 46/2500 = 23/1250

*November 4, 2016*

**Math**

the LCF for 16 and 40 is 8 so she could make 8 arrangement, each with 2 red roses and 5 white roses notice 8 x 2reds = 16 reds and 8 x 5whites = 40 whites all roses are used

*November 3, 2016*

**math**

4y = 4x - 6 y = x - 3/2 so your slope is 1 , and the y-intercept is -3/2 <---- you had that correct

*November 3, 2016*

**math**

so your new equation has the form y = ?? look at the given point, what is the y? y = 4

*November 3, 2016*

**Math**

4<x<7 double the x 8 < 2x < 14 add 3 11 < (2x+3) < 17 btw, the choices are poorly stated

*November 3, 2016*

**Math**

first we need the payment of the original mortgage i = .075/12 = .00625 n = 12(30) = 360 p(1 - 1.00625^-360)/.00625 = 200,000 I got p = 1398.43 1) the payment is $1398.43 , and the interest will depend on what payment period you are talking about. I will change. 2. We need the...

*November 3, 2016*

**Math**

candies are "discussed" evenly ?? So we are discussing the 360 candies between 50 students, and each student will get 360/50 which is not a whole number. Check your question.

*November 3, 2016*

**maths**

method: lee ---- x lal ---- x+10 dave --> (x+10) + 10 = x+20 x + x+10 + x+20 = 90 3x = 60 x = 20 etc

*November 3, 2016*

**math 7th grade**

no, you mixed up your units 2 cm/15 km = 6 cm/x km 2x cmkm = 90 cmkm 2x = 90 x = 45 or 2 cm ---> 15km 1 cm ----> 7.5 km 6 cm ----> 6(7.5) km or 45 km

*November 3, 2016*

**Math**

amount of sugar = 24(2) or 48 kg number of bags filled with sugar = 48/.5 = 96 amount of flour = 36(1) or 36 kg number of bags filled with sugar = 36/.25 = 144 So 96 will get a bag of each

*November 3, 2016*

**Ad. Functions**

let 2x = k then rewording the question: write 2sin(k)+?12cos(k) in the form of y= Acos(k-theta) Acos(k-Ø) = A(coskcosØ + sinksinØ) 2sin(k)+?12cos(k) = AcoskcosØ + AsinksinØ matching up terms 2sink = AsinksinØ 2 = AsinØ and ?...

*November 3, 2016*

**Math**

Samuel --- 4x oranges Daniel ----- 5x oranges 5x = 4x + 3 x = 3 Sam has 12, Daniel has 15

*November 3, 2016*

**Calculus**

total volume = cylinder + 2(hemispheres) = ?r^2 h + (4/3)? r^3 1600 = ?r^2 h + (4/3)? r^3 4800 = 3?r^2 h + 4? r^3 h = (4800 - 4? r^3)/(3? r^2) cost = 2(4? r^2) + 2? rh = 8? r^2 + 2?r(4800 - 4? r^3)/(3? r^2) = (16/3)? r^2 + 3200/r , not showing the simplification d(cost)/dr = (...

*November 3, 2016*

**go with Steve's - maths help**

go with Steve's solution

*November 3, 2016*

**maths help**

The first 3 terms in the expansion of (p+x)^n = p^n + n p^(n-1) x + n(n-1)/2 p^(n-2) x^2 + .. so we have: p^n = 3q ** n p^(n-1) x = 6qx ---> n p^(n-1) = 6q *** n(n-1)/2 p^(n-2) x^2 = 5q x^2, or n(n-1) p^(n-2) = 10q x^2 **** ** ÷ *** p/n = 1/2 ---> n = 2p *** &...

*November 3, 2016*

**Math: THIS IS SOOOOO HARD!!!!!!!!!!**

or 3/10 inches -----> 7/8 miles divide by 3/10 , which is the same as multiplying by 10/3 (3/10)(10/3) inches -----> (7/8)(10/3) miles 1 inch ----> 35/12 miles

*November 3, 2016*

**Maths**

Area of first triangle = (1/2)(15)(7) = 105/2 area of 2nd triangle = (1/2)(10.5)h (1/2)(10.5)h = 105/2 10.5h = 105 h = 105/10.5 = 10

*November 3, 2016*

**maths**

I will do one, you do the other slope CD = (12-0)/(-12-0) = 12/-12 = -1

*November 3, 2016*

**maths very hard**

I did this for you days ago http://www.jiskha.com/display.cgi?id=1477909974

*November 3, 2016*

**math 2**

not true, check with a calculator then check for typo

*November 3, 2016*

**calclus**

I will assume you meant y = 11(1+x^2) y = 11 + 11x^2 dy/dt = 22x dx/dt = 44x cm/s I will do a), you do the rest when x = -2 dy/dt = 44(-2) = -88 cm/s

*November 2, 2016*

**calculus**

same method as the one above this

*November 2, 2016*

**Calculus**

let the edge be x cm long V = x^3 dV/dt = 3x^2 dx/dt = 3x^2 (3) = 9x^2 cm^3/s so when x = 1 dV/dt = 9(1) cm^3/s do the 2nd part in the same way

*November 2, 2016*

**calculus**

let the height be h ft then diameter = 3h ft, and the radius is 3h/2 V = (1/3)? r^2 h = (1/3)? (9h^2/4)(h) = (3/4)? h^3 dV/dt = (9/4)? h^2 dh/dt when h = 15, dV/dt = 10 10 = (9/4)? (15) dh/dt dh/dt = 40/(135?) ft/s = 8?/27 ft/s

*November 2, 2016*

**Math, Precalc**

3^x + 5^(x+3) - 3^(x+4) + (1/3)5^(x+2)= 0 3^x(1 - 3^4) + 5^(x+2)(5 + (1/3)(1) ) = 0 -80(3^x) + (16/3)(5^(x+2) = 0 times -3/16 15(3^x) - 5^(x+2) = 0 15(3^x) = 5^(x+2) divide by 5 3(3^x) = 5^(x+1) 3^(x+1) = 5^(x+1) this can only be true if x = -1 that is, if 3^0 = 5^0 , which ...

*November 2, 2016*

**Math, Precalc**

Sue's time riding the bike = 5/15 hrs = 1/3 hr Sue's time walking the 2 miles = 2/3 hr total time = 2/3 + 1/3 = 1 hr total distance = 7 miles average speed = 7/1 = 7 mph

*November 2, 2016*

**Maths**

let the number of sides be n each interior angle = 180(n-2)/n each exterior angle = 360/n 180(n-2)/n < 10(360/n) by 84 180(n-2)/n = 10(360/n) - 84 times n, which is positive 180(n-2) = 3600 - 84n 180n - 360 = 3600 - 84n 264n = 3960 n = 15 sum of angles = 180(15-2)° = ...

*November 2, 2016*

**word problem**

48/16 = 3 72/12 = 6 so I can draw 18 rectangles of 12 by 16 on a piece of 48 by 72 BUT, using a regular saw there will be a saw-cut waste and that changes the question. I will assume your question is ignoring the sawdust.

*November 1, 2016*

**Pythagorean theorem**

depends on what the question is.

*November 1, 2016*

**Calculus**

f''(x) = x^2 f'(0) = 8, f(o)=4 if f''(x) = x^2, then f'(x) = (1/3)x^3 + c for the given: 8 = (1/3)(0) + c ---> c = 8 , and f'(x) = (1/3)x^3 + 8 f(x) = (1/12)x^4 + 8x + k f(0) = 4 4 = (1/12)(0) + 8(0) + k ----> k = 4 f(x) = (1/12)x^4 + 8x + 4 ...

*November 1, 2016*

**Calc**

height = -4.9t^2 + 10t + 2 d(height)/dt = -9.8t + 10 = 0 at max height 9.8t = 10 t = 10/9.8 height = -4.9(10/9.8)^2 + 10(10/9.8) + 2 = appr 7.102 m is the max height when it reaches the ground 0 = -4.9t^2 + 10t + 2 4.9t^2 - 10t- 2 = 0 t = (10 ± ?139.2)/9.8 = 1.306 ...

*November 1, 2016*