Saturday

July 23, 2016
Total # Posts: 35,337

**Math**

to get a sum of 5, we could have 1 4 2 3 3 2 4 1 so, prob(sumof 5) = 4/36 expected sum of 5 in 72 tries = (4/36)(72) = 8
*April 4, 2016*

**Transformations ALGEBRA**

to shift "up" 2 units, add 2 to the function f(x) = |x| + 3 + 2 f(x) = |x| + 5 What do you think we should do if we shift it 4 units down ?
*April 4, 2016*

**Algebra**

let the "certain" speed be x km/h then the distance between the two cities is 4x km time for return trip = 100/x + (4x-100)/(x-10) 100/x + (4x-100)/(x-10) - 4 = 1/2 100/x + (4x-100)/(x-10) = 9/2 multiply each term by 2x(x-10), the LCD 200(x-10) + 2x(4x-100) = 9x(x-10...
*April 4, 2016*

**Math Algebra 2**

I did this in a rather lengthy series of steps here. Steve has a more simplified version and also found an typo in mine http://www.jiskha.com/display.cgi?id=1459772906 my last 3 lines should have been v^2 = (c^2 m^2 - m0^2c^2)/m^2 v^2 = c^2 - m0^2c^2/m^2 v = c√(1 - m0^2/...
*April 4, 2016*

**Math-soh cab toa**

so 70 would be the hypotenuse of your right-angled triangle and you want the height, which is opposite your angle of 30° According to SOHCAHTOA sin30° = h/70 h = 70sin° = ....
*April 4, 2016*

**math**

Ms Sue and I both did this for you
*April 4, 2016*

**math**

distance = rate x time = 40(3.5) = 140 km Mmmmmhhhh, I doubt if you can get from Paris, France to London England in 3.5 hrs going at 40 km/h However, in southern Ontario where I live, there are a London and a Paris which happen to be about 100 km apart.
*April 4, 2016*

**math**

she did (4.6/48) miles/min = .0958.. miles/min or = 5.75 mph
*April 4, 2016*

**math**

That's the way the standard formula is. notice I had the correct answer.
*April 4, 2016*

**math**

That's a very creative formula you have there, but it makes no sense to me. You want the present value of monthly payments of $350 for 20 years at 6% compounded monthly PV = 350(1 - 1.005^-240)/.005 = 48,853.27 Btw, your P value turns out to be 319.50 Did you find that ...
*April 4, 2016*

**math**

Yes, I am one of the volunteer tutors on this site, we do not any definite time when you will find us. I answer mostly Math questions
*April 4, 2016*

**math**

if a sine of cosine curve is of the form y = a sin k(θ + c) + p you should memorize what what each of the a, k, c, and p represent None of your given functions have any verical shifts for all of them |a| is the amplitude the period is 2π/coefficient of x the only ...
*April 4, 2016*

**math**

see reply to your post above this one
*April 4, 2016*

**Business Math**

I don't have your handbook, but all you have to do is to compare the equivalent annual rates of the two accounts. No tables are needed annual rate for 12% per annum compounded quarterly = (1+.12/4)^4 = 1.1255% represents 12.55% annual rate for 14% compounded semi-annually...
*April 4, 2016*

**math**

just use common logic since we multiplied 3 by 5 to get 15 we have to multiply 40 by 5 to get 200 So 15 of them would cost 200 or 40/3 = x/15 3x = 600 x = 200 So, there is your cross-multiplication or, use the Unit way: if 3 mangoes cost 40 then 1 mangoe costs 40/3 and 15 ...
*April 4, 2016*

**math**

well, 1 1/4 dozen mangoes would be 15 mangoes. so if 3 of them cost 40.00 then 15 would cost ..... ?? (sure hope that is not $40.00 for 3 mangoes)
*April 4, 2016*

**help please**

If some sound is represented by a wave such as a sine or cosine wave, the amplitude of the trig function affects the loudness of the sound, the period of the trig function affects the pitch of the sound. so the larger the amplitude, the louder the sound. What is the greatest ...
*April 4, 2016*

**math**

Been there, seen it, done it look at the first Related Questions below
*April 4, 2016*

**Math**

I did this for you before you reposted. Always check back to see if your question has been answered before you post it again.
*April 4, 2016*

**add math**

a = 4t - 16 integrating ... v = 2t^2 - 16t + c given: at t=0, v = 30 30 = 0-0+c c = 0 velocity = 2t^2 - 16t + 30 when t=3 velocity = 2(9) - 16(3) + 30 = 0 looks like it is resting.
*April 4, 2016*

**Math Algebra 2**

m = m0/(sqrt (1 - (v^2/c^2)) ---> notice I fixed your mismatched brackets m(sqrt (1 - (v^2/c^2)) = m0 square both sides m^2(1 - v^2/c^2) = m0^2 expand m^2 - m^2 v^2/c^2 = mo^2 multiply each term by c^2 c^2 m^2 - m^2 v^2 = m0^2 c^2 c^2 m^2 - m0^2 c^2 = m^2 v^2 divide by m^2 ...
*April 4, 2016*

**Math**

let Sue's amount be x then Jane has x-20 and Harry has x-30 x + x-20 + x-30 = 160 solve this easy equation for x, and sub into my definitions
*April 4, 2016*

**Math**

slope between the first two points = (-3+4)/(1-0) = 1 checking for a second pair, 1st and last slope = (-1+4)/(3-0) = 1 I will let you check that the other 4 combinations yield the same slope of 1
*April 4, 2016*

**mathematics**

7(a+6d) = 11(a+10d) 7a + 42d = 11a + 110d -4a = 68d a = -17d term18 = a + 17d = -17d + 17d = 0
*April 4, 2016*

**algebra**

first piece --- x second piece --- 2x third piece --- 4x+3 solve x + 2x + 4x+3 = 38 it is easy.
*April 4, 2016*

**Algebra**

Hard to tell without the original question. As collins pointed out, your answer and the apparent correct answer do not match. State the original question and how you got your answer.
*April 4, 2016*

**precalc**

4^log16 7 = (16^(1/2))^log16 7 = (16)^((1/2))^log16 7) = 16^log16 sqrt(7) recall the property that a^loga k = k 16^log16 sqrt(7) = sqrt(7) or , using your calculator 4^log16 7 = 4^(log7/log16) = 4^.70183873 = 2.645751309 and sqrt(7) = 2.645751311 not bad
*April 4, 2016*

**geometry**

AB = sqrt(16^2 + 8^2) = 5sqrt(5) AC = sqrt(8^2 + 4^2) = 4sqrt(5) then CB = sqrt(5) C divides AB in the ratio of 4:1
*April 3, 2016*

**maths**

Just translate into Math using the definitions of AP "the fifth term is three times the second term " ---> a+4d = 3(a+d) a+4d = 3a+3d d = 2a ** "the sum of the first ten terms is 50" --> 5(2a+9d) = 50 2a+9d=10 *** sub ** into *** 2a+9(2a) = 10 20a=10 ...
*April 3, 2016*

**algebra**

Yes, I think I had that. Look at my definition of t
*April 3, 2016*

**algebra**

let the time taken by the cabin cruiser to catch up to the boat be t hours So 33t = 11(t+3) 33t = 11t + 33 22t = 33 t = 33/22 = 3/2 check: the boat went for 3+3/2 or 4.5 hours at 11 mph, went 49.5 miles the cruiser went for 3/2 hours at 33 mph, went 49.5 looks like it caught ...
*April 3, 2016*

**math**

-4x^2-4x+15 = -(4x^2 + 4x - 15) = -(2x - 3)(2x + 5) What method did you learn to solve a quadratic trinomial ?
*April 3, 2016*

**Math**

x^2 + 4x - 31 = a x^2 + 4x - 31 - a = 0 to have one root: 4^2 - 4(1)(-31-a) = 0 16 + 124 + 4a = 0 4a = -140 a = - 35 if f(x) = -35 x^2 + 4x - 31 = -35 x^2 + 4x + 4 = 0 (x+2)^2 = 0 x+2 = 0 x = -2 ----> only one root
*April 3, 2016*

**Math**

the way you typed it, the domain is the set of real numbers, x ≠ 0 What you probably meant is f(x) = (3x-7)/(x+1) In that case, the domain is the set of real numbers, x ≠ -1
*April 3, 2016*

**Math**

number of good ones --- x number of not-goods --- y cost = 7.5x + 7.5y return = 7.90x + 7.70y 7.9x + 7.7y - 7.5x - 7.5y = 34 .4x + .2y = 34 2x + y = 170 y = 170-2x There is no unique answer, unless you supply more information. I could pick any value of x between 0 and 85, and ...
*April 3, 2016*

**Algebra**

If the boat went 27 km, the raft went 17 km when they met. let the speed of the current (as well as the raft) be x km/h then the speed of the boat going upstream is 12-x km/h time taken by the raft = 17/x time taken by the boat = 27/(12-x) The difference in their times = 2 2/3...
*April 3, 2016*

**Math**

let the 3 numbers be x, y, and z from smallest to largest x+y+z = 18 z-x = 26/5 z = 26/5 + x into the first: x + y + 26/5 + x = 18 2x+y = 64/5 y = 64/5 - 2x = (64-10x)/5 but x, y, and z are to be mixed numbers, that is, they must all be greater than 1 so to find y, 64-10x >...
*April 3, 2016*

**Math**

youngest --- x oldest ---- 2x middle ---- x+3 x + 2x + x+3 = 27 solve for x
*April 3, 2016*

**Maths - calculus**

from the asymptote b/a = 18/5 , but b = 9 b/a = 9/2.5 x^2/(2.5)^2 - y^2/81 = -1
*April 3, 2016*

**Algebra**

Since both right sides are equal to y, we can say: 2x+2 = -2x-6 4x = -8 x = -2 back into y = 2x+2 y = 2(-2) + 2 = -2 x = -2, y = -2
*April 2, 2016*

**math**

careful with the notation: A statement such as 25-35 = 10 is incorrect , you have to say |25-35| = 10 that is where the "absolute" part of the definition comes in. Your arithmetic is fine.
*April 2, 2016*

**Math**

general principle of a fulcrum: If a mass of p units is placed x units from the fulcrum and it balances a mass of q units at y units on the oppose side from the fulcrum , then px = qy so make a sketch placing the 1 gram weights at the given distances The the fourth weight on ...
*April 2, 2016*

**math**

I agree
*April 2, 2016*

**Math**

Steve has answered several of these type of questions for you, here is just one of them where he showed you step by step how to do them. http://www.jiskha.com/display.cgi?id=1459622265 show us your steps you have taken for this question so we can see where your problems lie .
*April 2, 2016*

**Math**

number of nickels --- x number of dimes ----- 5x 5x + 10(5x) = 5775 solve for x, it is easy
*April 2, 2016*

**Algebra**

Oh for goodness sake! I proved to you that the answer is correct What do you mean by "I try to plug this answer in to the system " ?? What system? " it says it is incorrect" who is this "it" ??? show me the steps, perhaps I can see your error.
*April 2, 2016*

**Algebra**

You must be referring to http://www.jiskha.com/display.cgi?id=1459102205 I stand by my answer, I even proved at the end that it was correct. Have you considered that the text might be wrong?
*April 2, 2016*

**Math**

420 ft^2/f ft^2 = 36 min/30 min 420/f = 36/30 36f = 30(420) f = (30)(420)/(36) = 350
*April 2, 2016*

**Math**

3s + 9c = 75 ** 8s + 5c = 67 *** ** times 5 ---> 15s + 45c = 375 *** times 9 --> 72s + 45c = 603 subtract them: 57s = 228 s = $4.00 sub s = 4 into ** and solve for c
*April 2, 2016*

**math**

original fraction --- x/y new fractions ------- 1.6x/.8y = 2x/y it increased by 100% e.g. suppose the fraction was 5/8 new fraction = 1.6(5)/(.8(8)) = 8/6.4 = 80/64 = 10/8 ---> twice the 5/8
*April 2, 2016*

**Math**

#1 I will interpret that as: 2log (squarerootx) -log (4/3x^2) + log(4x^3)/log(100) = 2log x^(1/2) - (log4 - log3 - 2logx) + (log4 + 3logx)/2 = logx - log4 + log3 + 2logx + (1/2)log4 + (3/2)logx = (9/2)logx - (1/2)log4 = (1/2)(9logx - log4) or, = (1/2) log(x^9/4) = log [x^9/4...
*April 2, 2016*

**math**

p=log(squareroot8)/log(2) = log 8^(1/2) / log2 = (1/2)log 2^3 / log2 = (3/2) log2/log2 p = 3/2 log(31+log(16)/log(x))/log(9)=log(squareroot8/log(2) I see "mismatched brackets" on the right side. Where does p = 3/2 enter the picture?
*April 2, 2016*

**Maths**

area of whole circle = Pi(20)^2 = 400Pi Using a simple ratio: A/400Pi = 120/360 A = 400Pi/3 cm^2 = ....
*April 2, 2016*

**math( pls help me out)**

I disagree The probs that Bob found would each have 4 children, not three prob(of 3 children, two are girls) = C(3,2)(1/2)^2 (1/2) = 3/8 illustration: BBB BBG BGB GBB GGG GGB -- 2 GIRLS GBG -- 2 GIRLS BGG -- 2 GIRLS So there are 3 cases of 2 girls prob(2 girls) = 3/8 prob(3 ...
*April 2, 2016*

**another approach - math**

Ok, how about this approach sinA = x + cosA x = sinA - cosA let's change sinA - cosA into a single sinusoidal expression: Let sinA - cosA = a sin(A + k) a sin(A+k) = a(sinAcosk + cosAsink_ = asinAcosk + acosAsink then asinAcosk = sinA acosk = 1 cosk = 1/a acosAsink = -cosA...
*April 2, 2016*

**math**

I did this yesterday http://www.jiskha.com/display.cgi?id=1459511832
*April 2, 2016*

**Maths**

A 45 degree sector is 1/8 of the circle So find (1/8)(pi)(14^2)
*April 2, 2016*

**math**

prob(get money) = .3 prob(not get money) = .7 prob(at least 3 of 5 get money) = C(5,3)(.3)^3 (.7)^2 + C(5,4)(.3)^4 (.7) + .3^5 = .. you do the button-pushing
*April 2, 2016*

**Math**

by simple observation, the x's increase by 2 , so 20+p = 21 thus p=1 which lets the y's increase nicely by 1
*April 2, 2016*

**math**

prob(buy) = .4 prob(not buy) = .6 prob(5 of 10 will buy) = C(10,5) (.4)^5 (.6)^5 = 252(.000796..) = appr .2007
*April 2, 2016*

**Algebra**

in the first, replace x with -3 and solve for y in the second, replace y with 1 and solve for x
*April 1, 2016*

**Math**

distance from (3,4) to (-1,0) = sqrt(4^2 + 4^2) = sqrt(32) = appr 5.7 where you just guessing?
*April 1, 2016*

**Math- quadratic equation**

width of pathway = x m width of whole thing = 12+2x m length of whole thing = 16+2x (12+2x)(16+2x) = 258 192 + 56x + 4x^2 = 258 2x^2 + 28x - 33 = 0 x = (-28 +- sqrt(1048))/4 = 1.093 or a negative the path should be appr 1.09 m wide all around check: (12+ 2.18)(16+2.18) = 14.18...
*April 1, 2016*

**Math**

looks like for every increase of 1 in the x, our y decreases by 5 so it must be y = -5x + c all we need is to find c pick one of the data values: 0 = 0, y = -1 -1 = 0 + c c = -1 y = -5x - 1
*April 1, 2016*

**trigonomentry out of ideal help ah!crying**

cute problem recall that cos x = - cos(180 - x) that is cos(1) = - cos(179) cos(3) = - cos(177) .. cos(89) = - cos(91) cos(91) = - cos(89) ... cos(177) = - cos(3) cos(179) = - cos(1) so : cos1 + cos3 + ... + cos 177 + cos 179 = (cos1+cos179) + (cos3+cos177) + ...+ (cos89+cos91...
*April 1, 2016*

**typo - Math**

I did this on paper first, but then messed up when I typed it. the first few lines in the equations should have been: (x+1)(x - (1+i))(x - (1-i)) = 0 (x+1)(x-1-i)(x-1+i) = 0 (x+1)(x^2 - x + xi -x +1 -i -xi + i - i^2) = 0 the rest is fine
*April 1, 2016*

**Math**

complex roots always come in conjugate pairs, so if one is 1+i, you must have another as 1-i so we know the equation is (x+1)(x - (1+i))(x + 1+i) = 0 (x+1)(x-1-i)(x+1+i) = 0 (x+1)(x^2 + x + xi -x -x -i -xi - i - x^2) = 0 (x+1)(x^2 - 2x + 2) = 0 x^3 - x^2 + 2x + x^2 - 2x + 2 = ...
*April 1, 2016*

**Mathematics**

trying your choice: for (2,-1) in y = 2x - 1 -1 = 2(2) - 1 -1 = 3 ???? not every likely. try the others the same way.
*April 1, 2016*

**Math**

Since the sine is negative and the tangent is positive, the angle is in quadrant III from sin theta = -4/9, r = 9 and y = -4 x^2 + y^2 = r^2 x^2 + 16 = 81 x = -sqrt(65) , in III the x is negativ Then cos theta = -sqrt(65)/9 sec theta = -9/sqrt(65) or -9sqrt(65)/65
*April 1, 2016*

**math**

let sinA = x + cosA x = sinA - cosA x^2 = sin^2 A - 2sinAcosA + cos^2 A x^2 = 1 - 2sinAcosA x^2 = 1 - sin 2A x = +/- sqrt(1-sin(2A)), |sin 2A| <= 1 not sure if that is what you want. Since I squared the equation, any (A,x) would have to be verified
*April 1, 2016*

**math**

Since no letters repeat, this is straightforward. number of "words" = 9! = 362880
*April 1, 2016*

**Math**

4 queens or 4 fives prob(of stated event) = 8/52 = 2/13
*April 1, 2016*

**Math**

In any of these kind of problems , n has to be a whole number, that is n = 1,2,3, .... My choice would be term(n) = 5n - 1 , which is the only one that makes term(1) = 5(1) - 1 = 4 your choice would produce a first term of 9, which is the second term, not the first your ...
*March 31, 2016*

**Algebra 2**

interpretation: the division must be excact, that is, there cannot be a remainder. Arrange the terms in the proper order and do a synthetic division: -1 | -2 1 -1 1 ....... 2..-3..4 .... -2 3..-4..5 so we should have had a 0 instead of a 5 at the end of our algorithm, that ...
*March 31, 2016*

**Math**

A is the only one that works our pattern.
*March 31, 2016*

**Math**

#1 notice that the terms keep getting smaller, so we clearly are adding a -6 What number did we start with? #2 the correct choice would be -64, -128, -256 which I don't see, unless you have a typo
*March 31, 2016*

**Pre cal 11**

let 5b-3 = x, then we have 4x^2 + 10x - 6 = 2(2x^2 + 5x - 3) = 2(x+3)(2x-1) replace x with 5b-3 within each bracket , then simplify
*March 31, 2016*

**Calculus**

If your function contains terms of the type ax^2, ay^2, ax, and ay along with some constant terms , and where a is a rational number, then you have a conic if it contains terms such as xy , it could be a conic that has been rotated, and is no longer parallel or perpendicular ...
*March 31, 2016*

**Maths**

What the question does not say, but what I will assume is true to have your answer of 10, is that the dimensions must be whole numbers. Otherwise there would be an infinite number of cases So we need 3 multipliers (LWH) to get 28 the factors of 28 in triples are 1 1 28 1 2 14 ...
*March 31, 2016*

**math**

For the 10 K race in 58 minutes the runner would take 5.8 minutes per km or 5 minutes and 48 seconds to run 1 km The equivalent race of 6.2 miles would have a time of 58/6.2 minutes per mile or 9.3548.. minutes per mile = 9 minutes, 21 seconds (A real runner doing a 10 K race ...
*March 31, 2016*

**math**

the average of 200 and 160 is 180 so the speed of the plane with no wind is 180 mph, and the wind speed is 20 mph check: going against the wind = 180-20 = 160 going with the wind = 180 + 20 = 200
*March 31, 2016*

**@ AMANSANDHUWILLDIE - pr calc 11**

You might have noticed that Steve did not reply to your question. You may talk in a disrespectful way to your peers the way you did, but calling a distinguished professor "dude" is not the smartest thing to do. I am sure one of your fellow dudes might suggest that ...
*March 31, 2016*

**Math**

hearts OR ten = 13 + 4 - 1 = 16 (can't count the 10 of hearts twice) continue
*March 31, 2016*

**Geometry**

Oh my goodness! What has happened to each of the coordiates of the two points? Why was 6 your choice? How can you "feel" an answer to be right?
*March 31, 2016*

**Math**

I was able to see your diagram. Since the band circle must have a total of 25, and we have already (11+7+3) or 21 entered in the Venn diagram, the missing part of Band and Choir must be 4 So label the math-only part 9 and the intersection of Math and Choir as x (only the part ...
*March 31, 2016*

**Math**

Look at the previous post and simply change the numbers
*March 31, 2016*

**Math**

The number of ways to select 7 from 1 to 45 = C(45,7) = 45,379,620
*March 31, 2016*

**math**

The HCF of 64 and 124 is 4 The LCM of 64 and 124 is 1984 so what is 1984/4 ?
*March 31, 2016*

**business math**

100(r)(2/52) = 2.50 r = (2.5/100)(52/2) = .65 = 65% The equivalent annual rate is 65% (In the middle ages they would have been burned at the stake for usury.)
*March 31, 2016*

**Math**

wins --- x ties --- y x+y= 18 2x+y= 30 subtract them: x = 12 then y = 6 wins: 12 losses: 10 ties: 6 check: 2(12) + 0(10) + 1(6) = 30
*March 31, 2016*

**Trig**

make sketches of two right angles triangles in the third quadrants since tanA = 3/4, the terminal arm of angle A ends at (-4,-3) , and r = 5 so sinA = -3/5, and cosA = -4/5 (you have a 3-4-5 right-angled triangle) since cosB = -5/13 , the terminal arm of angle B ends at (-5,-...
*March 31, 2016*

**Math**

term(n) = -3n + 27
*March 31, 2016*

**math**

.05(3000) + .08x = .075(3000+x) 150 + .08x = 225 + .075x .005x = 75 x = 15,000 check: total invested = 3000+15000 = 18000 .075(18000) = 1350 interest at partial investments = .05(3000) + .08(15000) = 150 + 1200 = 1350 How did you possible get $279,375 ??? Did that sound ...
*March 31, 2016*

**Algebra**

x + (1/7)x = 88 hint: multiply each term by 7 to clean up the fraction, and solve for x
*March 31, 2016*

**Algebra 1-Factoring Help!**

Somebody had the same question earlier today. http://www.jiskha.com/display.cgi?id=1459354736
*March 30, 2016*

**math**

correct, 10% of 80 is 8 so prob of fail = 8/80 = 1/10 so for 400 units, prob = (1/10(400) =
*March 30, 2016*

**math**

what is 10% of 80 ?
*March 30, 2016*

**Math**

looks like a simple typo here actually 4/52 = .0769... = .08 correct to 2 decimals
*March 30, 2016*

**NO - Math**

no The order in which the cards are drawn should not matter. They even used the word "combination", which implies that the order does not matter. So you are simply choosing 2 of the 9 cards = C(9,2) = 9!/(2!7!) = 36 The answer of 72 would be correct if the order in ...
*March 30, 2016*

**Math**

cylinder1: height = h radius = r volume = pi r^2 h = pi r^2h cylinder2: height = h radius = 2r volume = pi (2r)^2 h = 4pi r^2h or ratio is 1 : 4 so the volume is 4 times as large
*March 30, 2016*