Thursday

June 30, 2016
Total # Posts: 35,111

**Math**

number of stickers ---- x number of ballons --- 6x bubbles ----- (1/3)(6x) = 2x x + 6x + 2x = 135 solve for x
*April 7, 2016*

**Math**

I assume you mean by just guessing. he must get 8 right, or 9 right or 10 right = C(10,8)(1/2)^8 (1/2)^2 + C(10,9)(1/2)^9(1/2) + C(10,10) (1/2)^10 = (1/2)^10 ( 45 + 9 + 1) = 55(1/2)^10 = 55/1024 not good, better study
*April 7, 2016*

**Math**

let the side of square ABCD be x then area = x^2 area of square EFGH = 2x^2 side of square EFGH = √2 x EF = √2 x AC^2 = x^2 + x^2 = 2x^2 AC = √2 x AB/AC = x/√2x = 1/√2 AB/EF = x/√2x = 1/√2 thus AB/AC = AB/EF
*April 7, 2016*

**Math**

original price ----- x dollars .85(1.08)x = 688.50 solve for x
*April 7, 2016*

**Math**

In a refection over the x-axis, the x coordinate would stay the same, but the y would turn into its opposite that is, (x,y) ---> (x, -y) A(2,-5) ---> A'(2,5) find the choice that matches this
*April 7, 2016*

**pre ap math**

If it is lauched from a height of 48 ft, then the equation should be h = -16t^2+32t+48 I will assume a typo you want h = 0 (at ground level h=0) 0 = -16t^2+32t+48 t^2-2t-3 = 0 It factors, (t-3)(t+1) = 0 t = 3 or t = -1, rejecting the negative time it took 3 seconds
*April 7, 2016*

**linear equations in one variable**

Let the number of ₹5 coins be x then the number of ₹2 = 3x and the number of ₹1 = 160 - x - 3x = 160 - 4x Now for the value: 5x + 2(3x) + 1(160 - 4x) = 300 5x + 6x + 160 - 4x = 300 7x = 140 x = 20 You have 20 ₹5 coins 60 of the ₹2 coins and 80 of ...
*April 7, 2016*

**math probability**

The prob that you get a 7 when rolling two dice = 1/6 so when two friends roll , (the same result as you rolling twice) prob(2 7's ) = (1/6)(1/6) = 1/36
*April 7, 2016*

**math**

area of trap = (1/2)(sum of parallel sides)(distance between them) (1/2(a + 12)(6) , where a is the other parallel side. (1/2(a + 12)(6) = 48 3(a+12) = 48 3a + 36 = 48 3a = 12 a = 4
*April 7, 2016*

**math**

Am I looking at 3 equations? separate them with commas. what is 3y+x-×=10-x ? is x-× a power like x^-x ??
*April 7, 2016*

**Precal**

Don't you have a calculator? make sure you catch the double negative in the last term since cos 135 is negative
*April 7, 2016*

**Math-soh cah toa**

make a sketch. label the ends of the bridge A and B make angle A = 41° and angle B = 48°. label the point on the river P and Q on AB so that PQ is at right angles to AB. Let PQ = h let QB = x , the AQ = 140-x tan41 = h/(140-x) h = (140-x)tan41 tan48 = h/x h = xtan48 So...
*April 7, 2016*

**Math**

I will do one of the components, you do the other , then subtract them a(x) = 3x - 7 and b(x) = 2 - x^3 a(b(3)) = a(2-3^3) = a(-25) = 3(25) - 7 = 68
*April 7, 2016*

**Math**

just follow the definition: f(a,b) = 2a - 3b^2 + 7 f(b,3) = 2b - 3(3)^2 + 7 = 90 2b - 27 + 7 = 90 2b = 110 b = 55
*April 7, 2016*

**Math**

y = 5x-12 inverse: x = 5y-12 5y = 12-x y = (12-x)/5 f^-1 (x) = (12-x)/5 f(x+1) = 5(x+1) - 12 = 5x - 7 5x-7 = (12-x)/5 25x - 35 = 12 - x 26x = 47 x = 47/26 check my arithmetic
*April 7, 2016*

**Math**

We are told : a#b=ab-a-b+1 so x#7 = 7x - x - 7 +1 = 42 6x = 48 x = 8
*April 7, 2016*

**Math**

x^2 + 12x = 73 let's complete the square, the easiest way to solve this particular one x^2 + 12x + 36 = 73+36 (x + 6)^2 = 109 x + 6 = ± √109 x = -6 ± √109 the positive one looks like √109 - 6 so a = 1, b = -6 a+b = -5
*April 7, 2016*

**Math**

What part of my solution I gave you here did you not like ? http://www.jiskha.com/display.cgi?id=1459995714
*April 7, 2016*

**Geometry**

did you notice that you are given two angles in each of the triangles ? Did you notice that their sum is 180 degrees? So they are similar, thus the corresponding sides are proportional. What are we supposed to find ?
*April 7, 2016*

**Algebra II**

Show Thomas a simplified example of why his idea is wrong 3^2 + 4^2 = 5^2 ---- true then 3 + 4 = 5 ????? If you want to take the square root, you have to take it of the whole side, not the individual terms
*April 7, 2016*

**Calculus**

f'(-4) = 9 f'(0) = 6 f'(x) = 3ax^2 + 2cx f'(-4) = 48a - 8c = 9 f'(0) = 0 + 0 = 6 Oh, oh, something fishy here. Check your typing or check the question
*April 7, 2016*

**Calculus**

f(x) is increasing if f'(x) is positive so (x−8)^7(x−1)^4(x+19)^8 > 0 we know that (x−1)^4(x+19)^8 is always positive since we have even exponents. So all we have to do is look at (x-8)^7 > 0 if x > 8 then (x-8)^7 > 0 if x < 8 it is ...
*April 7, 2016*

**Calculus**

f(x) = √(36-x^2) = (36-x^2)^(1/2) f ' (x) = (1/2)(36-x^2)^(-1/2) (-2x) = 0 for a max/min thus x = 0 , f(0) = 6 but f(1) = √(36-1) = √35 which is < 6 f(6) = √0 = 0 So the absolute minimum is 0
*April 7, 2016*

**math**

in a), b), and d) the first points don't work leaving c) in c) the 2nd point does not work so none of triples have all 3 correct
*April 7, 2016*

**math**

the way you typed according to BEDMAS (1/15)(6+x)=(1/6)(x+3) multiply both sides by 30 2(6+x) = 5(x+3) now it is easy, carry on What Bob meant was: did you mean, 1/(15(6+x)) =1/(6(x+3)) ? then we have an entirely different ballgame
*April 7, 2016*

**math**

All of them are NOT a solution
*April 7, 2016*

**check this - maths**

I must have made some kind of error in this big mess. I can't reconcile the fact that k = 6 will produce the 45 degree angle, but both of our solutions somehow showed that k = 2 I will look at it again later on today
*April 7, 2016*

**maths**

x^2 + xy - Ky^2=0 To have this equation represented by two straight lines, we must have it in a factored form such as (x + ay)(x - by) = 0 so that a+b = 1 and ab=-k e.g. if we had x^2 + xy - 6y^2 = 0 (x+3y)(x-2y) = 0 our two lines would be x+3y = 0 or x-2y = 0 slope of first...
*April 7, 2016*

**Algebra**

Winner of the most nonsensical question of the day.
*April 6, 2016*

**Math**

amount = 1500 + 1500(1.05^4 - 1)/.05 = 7965.19
*April 6, 2016*

**Math**

x^2 - 5x - 4 < 10 x^2 - 5x - 14 < 0 (x-2)(x+7) < 0 if y = (x-2)(x+7) we have a parabola opening upwards with x-intercepts of 2 and -7 the parabola would be below the x-axis, that is y < 0 , for -7 < x < 2
*April 6, 2016*

**Math**

the maximum area is obtained when your rectangle is a square. so let the side be s 4s = 24 s = 6 area = 36
*April 6, 2016*

**Math**

again, just like in your last post, just do it m/n@p/q = (m)(p)(q/n) 7/69@23/24$ , other than the confusing $ = 7(23)(24/69) = 56
*April 6, 2016*

**Math**

What's wrong with just plugging in the numbers and adding the fractions?
*April 6, 2016*

**math**

the last one looks just like http://www.jiskha.com/display.cgi?id=1459986016 but you changed the first term so the answer is not 2779 like in your previous question for the bagel question, which I did for you here http://www.jiskha.com/display.cgi?id=1459985491 how did you get...
*April 6, 2016*

**Math**

A(2) = 3 - 2(2)^2 - 4^2 = 3 - 8 - 16 = -21 find A(1) the same way, then subtract them
*April 6, 2016*

**Geometry**

Follow my steps in your previous post http://www.jiskha.com/display.cgi?id=1459994336
*April 6, 2016*

**Trig**

let the length of the chord be 2x ft Drop a perpendicular from the central vertex to the chord then sin 12.5 = x/30 x = 30sin12.5 2x = 60sin12.5 = 12.9864 or by cosine law: let the length of the chord be c c^2 = 30^2 + 30^2 - 2(30)(30)cos25 = 168.64598.. c = 12.9864 , same as ...
*April 6, 2016*

**Geometry**

let the width of the uniform border be x ft new width = 10+2x new length = 15 + 2x area of whole thing = (10+2x)(15+2x) (10+2x)(15+2x) - 150 = 100 150 + 50x + 4x^2 - 15 - 100 = 0 4x^2 + 50x - 100 = 0 2x^2 + 25x - 50 = 0 doesn't factor, so use the formula x = (-25 ±...
*April 6, 2016*

**Math**

let number of boys be 5x let numbe of girls be 3x after change: boys --- 5x+1 girls --- 3x+3 (5x+1)/(3x+3) = 4/3 15x + 3 = 12x + 12 3x = 9 x = 3 new class : boys = 16 girls = 12 total = 28
*April 6, 2016*

**math**

-3/4-(3/-8) = -3/4 + 3/8 = -6/8 + 3/8 = -3/8
*April 6, 2016*

**correction - Math**

scrap the 7,5,1,1 combination, they don't add up to 12 also scrap the 7,1,1,1,1, there should only be 4 digits.
*April 6, 2016*

**Math**

add = odd ?? notice that 12 = 7+5+1+1 or 12= 3+5+3+1 12 = 7+3+1+1 12 = 9+1+1+1 see if you can find any others. now each of my choices can be arranged in different orders 7,5,1,1 ---> yields 4!/2! or 12 of them 3,5,3,1, yields 4!/2! = 12 of them 7,1,1,1,1 etc one of them is ...
*April 6, 2016*

**Geometry**

Algebraic way: original width = x original length = 2x+3 x(2x+3) = 434 2x^2 + 3x - 434 = 0 (x - 14)(2x + 31) = 0 x = 14 or x = -31/2 , which I will reject original width is 14 ft original length is 31 ft new width = 18 new length = 35
*April 6, 2016*

**Algebra**

notice for each increase of 2 units of tem, the level drops 10 rate of change = -10/2 ft/h = -5 ft/hr
*April 6, 2016*

**Algebra**

between which readings ?
*April 6, 2016*

**Geometry**

ok, ok I stand corrected, there is a way, we have an angle. The apothem is the distance from the centre to the midpoint of a side Let's look at one of the triangles of the hexagon. It has a central angle of 60 so in a right-angled triangle formed by the apothem and half ...
*April 6, 2016*

**Geometry**

So, I guess we can't find the area, since we need the side
*April 6, 2016*

**Geometry**

Area = 1/2 x perimeter x apothem = 1/2 (6s)(6√3) once you tell me what the side (s) of the hexagon is, we an finish the question
*April 6, 2016*

**Algebra**

confusing wording Anyway, for y = mx + b m is the slope, or the rate of change the greater the value of m, the greater the rate of change.
*April 6, 2016*

**math**

looks like an AS with a = 4.5 and d= .5 term(5550) = a + 5549d = 4.5 + 5549(.5) = ....
*April 6, 2016*

**math**

2c + 4b = 600 2c + 7b = 825 subtract them: 3b = 225 b = 75 sub b = 75 back into the firs equation and solve for c let me know what you get.
*April 6, 2016*

**Precal**

We don't "work this out" I believe this is an identity, so we have to prove LeftSide = RightSide If it is an identiy, if we attempt to "solve" it, we end up 0=0 LS = cot^3 x+ cotx = cotx(cot^2 x + 1) = (cosx/sinx)((cos^2 x/sin^2 x + 1) = (cosx/sinx)(cos...
*April 6, 2016*

**Algebra**

credit cards with 7.5% and 6% interest rates? Must be some alternate universe. Anyway... amount charged at 6% card --- x amount charged at other card -- 2x .06x + .075(2x) = 840 .06x + .15x = 840 .21x=840 x = 4000 She charges $4000 at the 6% card and $8000 at the 7.5% card
*April 6, 2016*

**College Algebra**

A, C, and D are correct B: 3f(-1) = 3[(-1)^2 + 3(-1)] = 3[1 - 3] = 3(-2) = -6 E) x^2 + 3x = 4 x^2 + 3x - 4 = 0 (x+4)(x-1) = 0 x = -4 or x = 1 checking for x = -4 f(-4) = (-4)^2 + 3(-4) = 16-12 = 4 , checks! try for x = 1 the same way, you should get 4 as well
*April 6, 2016*

**Trigonometry**

You will have to use a calculator for this one. if cosx = .1 then x = 84.26° correct to 2 decimals but cosine is positive in I or IV so x = 360-84.26 = 275.74° x = appr 84.26 or 275.74
*April 5, 2016*

**maths**

adding/subtracting of degrees works like add/subtract in units of time we have to "borrow" a degree 22degrees33' - 10degrees54' = 21° 93' - 10° 54' = 11° 39' look at your calculator If you have a key labeled D°M'S then you can ...
*April 5, 2016*

**Probability (check)**

That would be 4C2 , four choose two, or C(4,2) = 4!/(2!2!) = 6
*April 5, 2016*

**Algebra**

(4y^2z^3-8yz^2)/(yz^2-2z) = 4yz^2(yz - 2)/(z(yz - 2)) = 4yz^2/z = 4yz , z ≠ 0, yz ≠ 2
*April 5, 2016*

**math**

following BEDMAS 3/8 * 1/4 / 3/4 + 1/5 = 3/32 / 3/5 + 1/5 = 1/8 + 1/5 = 13/40
*April 5, 2016*

**math**

let his gain in third month be x -15.45 + 35.68 + x = 40 x = 19.77
*April 5, 2016*

**calculus**

let y = √( 25-x^2) = (25-x^2)^(1/2) dy/dx = (1/2)(25-x^2)^(-1/2) (-2x) = -x/√(25-x^2) = 0 for a max/min thus x = 0 and f(0) = √25 = 5 I will let you decide if (0,5) is a max or a min You might want want to look at a quick sketch of the function to easily ...
*April 5, 2016*

**calculus**

If you are studying Calculus, you should make an effort to memorize the ratios of two important triangles: 1. the 45-45-90 degree triangle, with sides 1 : 1 : √2 corresponding to the angles 2. the 30-60-90 degree triangle, with sides 1 : √3 : 2 so in this case if ...
*April 5, 2016*

**college algebra**

R = k L/d^2 given case: L = 300, d = .05, R = 30 30 = k (300/.05^2) k = .0025(30)/300 = .00025 R = .00025 L/d^2 a) plug in the given values to find R b) plugging in our values: 20 = .00025 L/.03^2 L = .0009(20)/.00025 = 72 the wire is 72 inches long
*April 5, 2016*

**math**

3 miles take 27 minutes 1 mile would take 27/3 or 9 minutes thus 10 miles would take 90 minutes
*April 5, 2016*

**math**

Use the distance between 2 points formula It is in your text or in your notes
*April 4, 2016*

**Math PLZ**

x and y are whatever YOU define them as. For this question, using 2 variables is more difficult than using just one I would let x be the number of dimes. then the number of nickels is x+4 (it said so) Now form your equation using the value of those coins 10x + 5(x+4) = 95 15x...
*April 4, 2016*

**Pre-Algebra**

prob(getting a 4 ) = 1/6 so in 200 tries, number of times a 4 should show up = (1/6)(200) = 33 1/3 It said "about" how many times, so I would say about 33 times
*April 4, 2016*

**Algebra**

number of subsets for 3 elements = 2^3 = 8 which would include the null set and the entire set. So we have to include the null set {}, and the entire set {3,7,2}
*April 4, 2016*

**Math**

If you have to use all 9 coins, the solution you gave is the only one to produce 60 cents, and use all 9 coins If you can use any number of your 9 coins, then 2 quarters 1 dime 0 pennies would be an option To prove that there is only 1 way using all 9 coins, consider this ...
*April 4, 2016*

**Math**

Damon, I still have mine ! btw, that should have been log3 (5m)
*April 4, 2016*

**Trigonometry**

if sinx = 4cosx sinx/cosx =4 tanx= 4 = 4/1 sketch a right-angled triangle with opposite 4 and adjacent 1 then r^2= 4^2 + 1^2 r = √17 then sinx = 4/√17 , cosx = 1/√17 sinxcosx = (4/√17)(1/√17) = 4/17
*April 4, 2016*

**Math/Algebra**

just use a simple ratio x/420 = 1/(5/6) = 6/5 cross-multiply 5x = 2520 x = 504
*April 4, 2016*

**geometry**

Well, you said it was a right-angled triangle, so the largest angle is 90° the sum of the other two must be 90° 3x+4 + 4x+2 = 90 solve this simple equation for x, then sub in the 2 different expressions
*April 4, 2016*

**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*