Friday

July 1, 2016
Total # Posts: 35,112

**ALGEBRA**

-5x-9y=-21 -- times 7 ---> -35x - 63y = -147 7x + 5y = -1 -- times 5 ---> 35x + 25y = -5 add them: -38x = -152 x = 4 sub into the original 2nd to get y
*June 30, 2016*

**math**

According to your garbled wording the number is 333
*June 30, 2016*

**Maths**

I read it differently. First we have to choose (combination) 3 of the 8 cities, which is C(8,3) or 8C3 = 56 (where did you get 12 cities ?) now for each of those choices, he can schedule the order of visit (permutation). Each choice can be arranged in 3! or 6 ways. number of ...
*June 30, 2016*

**math equation**

"If the side of a square are extended to form a rectangle." ?? A sentence that begins with "If ..." must end with "then ...." let the new sides be x+5 and x+2 (x+5)(x+2) = 130 x^2 + 7x + 10 - 130 = 0 x^2 + 7x - 120 = 0 (x-8)(x+15) = 0 x = 8 or x ...
*June 30, 2016*

**Math**

Set up a proportion equation: m = kw, where m is the amount of medicine, and w is the body weight, k is a constant for m = 205, w = 164 205 = k(164) k = 205/164 = 5/4 m = (5/4)w when m = 173.75, 173.75 = (5/4)w w = 139 or just use a simple ratio: w/164 = 173.75/205 w = 164(173...
*June 30, 2016*

**Math**

(x+73+60+86)/4 = 72 solve for x
*June 30, 2016*

**Math**

Are you studying vectors? the resulting velocity vector is (4,0) + (0,3) = (4,3) magnitude of vector = √(4^2+3^2) = √25 = 5 time to go 1 km at 5 km/h = 1/5 hours or 12 minutes angle between the resultant an normal: tanØ = 3/4 Ø = 36.87° for ...
*June 30, 2016*

**Math(HELP PLEASE )**

Is your table supposed to be a partial solution set to the given equation? If so, then only (-1,13) satisfies the equation , the other two points do not. Just rewrite the equation to the form y = -4x + 9 now pick any x you feel like, sub it in and you have another entry for ...
*June 30, 2016*

**Math**

There are an infinite number of solution pairs to your equation. From your post all of them are missing. One of them is (0,1) another is (3.8 , -7.55)
*June 29, 2016*

**Math**

This is a classic Distance-Rate-Time problem let the speed of slower train be x mph then speed of faster train is x+12 mph 2x + 2(x+12) = 400 solve for x
*June 29, 2016*

**Math**

quarterly rate = .10/4 = .025 = i number of payments = 4(5) = 20 = n amount = 70( 1.025^20 - 1)/.025 = ...
*June 29, 2016*

**Maths**

cost = 370 because of the 2.5% loss due to wastage, they only sold 97.5% of the fertilizer return = .975(1000)(.61) = 584.75 profit = 224.75 Percentage profit = 224.75/370 = appr 60.7 %
*June 29, 2016*

**Math**

amount sold by Susan ---- x L amount sold by William ---- (x+6.84) L amount sold by Tim ------ (x+18.3) L a) solve x+6.84 = 21 b) add them up and sub in your solution for x
*June 29, 2016*

**algebra**

Use your formulas. a+d = 24 a+4d = 3 subtract them: 3c = -21 d = -7 in a+d=24 a=7=24 a = 31 first term is 31, common difference is -7
*June 29, 2016*

**Math**

a+3d = 24 a+11d = 56 subtract them: 8d = 32 d = 4 sub into one of the above equations to find a
*June 29, 2016*

**math**

Look up "how many yards in a km" (After all, you are on a computer to post this ) btw, I did this on Moday http://www.jiskha.com/display.cgi?id=1467023818
*June 29, 2016*

**Math**

done http://www.jiskha.com/display.cgi?id=1467199616 why are you switching names?
*June 29, 2016*

**Maths**

height ---- h shadow length ----- √3 tanØ = h/√3h = 1/√3 Ø = ?? you should be familiar with the angle whose tangent is 1/√3 btw, I suspect a typo in 1√3, since we normally would not put that 1 in front of a radical. was it 1/√3...
*June 29, 2016*

**math**

really ?
*June 29, 2016*

**math**

Since in a code, the order matters, it would be 4x3x2 or 24
*June 29, 2016*

**Differential Calculus**

let the width of the rectangle be x m let the base of the rectangle be 2y m, making the radius of the semicircle equal to y m (my semicircle sits on the y ) 2x + 2y + (1/2)(2πy) = 10 2x + 2y + πy = 10 y(2 + π) = 10 - 2x y = (10-2x)/(2+π) area = 2x(2y) + (1/...
*June 28, 2016*

**math**

I assume she only needs fencing along 3 sides of the rectangle, plus a semicircle on the longer side. perimeter = 30 + 2(12) + (1/2)(2π(15)) = 54 + 15π or appr 101.12 m
*June 28, 2016*

**math**

yes
*June 28, 2016*

**math**

solve: 2x + 3x + 100 = 180 then find 2x and 3x
*June 28, 2016*

**Algebra**

smaller ---- x larger ------ x+3 4(x+3)/x = 2 4x + 12 = 2x carry on
*June 28, 2016*

**math**

8P5 ----> found on your calcualtor = P(8,5) ----> found on some Calculators = = 8!/3! = 6720
*June 27, 2016*

**math**

number of such numbers = 7x6x5x4 = 7!/3! = P(7,3) = 210 , as Steve stated
*June 27, 2016*

**calculus**

rectangle open on one side ?? Poor wording, I will assume that this is the "classic" problem where you have perimeter on only 3 sides, such as the rectangle is against a building. b = 40 - 2h A = bh = h(40-2h) = -2h^2 + 40h dA/dh = -4h + 40 = 0 for a max of A 4h=40 h...
*June 27, 2016*

**Math**

x^2+y^2-12x-10y = -12 x^2 - 12x + 36 + y^2 - 10y + 25 = -12+36+25 (x-6)^2 + (y-5)^2) = 49 new circle needs a radius of 5, so (x-6)^2 + (y-5)^2 = 25 Please tell me what you did to work on this "all day" .
*June 27, 2016*

**Math**

number of units ---- x cost = 950x + 60,000 we want 1700x ≥ 950x + 60000 750x ≥ 60000 x ≥ 80 At 80 units they break even, at more than 80 they make a profit
*June 27, 2016*

**math**

Steve took a guess at what you meant http://www.jiskha.com/display.cgi?id=1466985460 you ignored his reply and just reposted. what is "sim 17" supposed to be ??
*June 27, 2016*

**math**

traditional method: a+d = 24 a+4d = 3 subtract them: 3d = -21 d = -7 sub into a+d = 24 a - 7 = 24 a = 31 first term is 31, commond difference is -7
*June 27, 2016*

**math**

9,000,024 km = 9,000,024(100,000) cm = 9,000,024(100,000)/2.54 inches = 9,000,024(100,000)/(2.54(36)) yards = ... you do the button pushing
*June 27, 2016*

**Please help immediately! Math**

I see 6 rectangles + 2 hexagons area of one hexagon = 6(1/2)(9)(7.8) = ... take over
*June 27, 2016*

**Urgent help here! Math**

270kg of corn would feed 42 horses for 21 days 270kg of corn would feed 21 horses for 42 days 1 kg of corn would feed 21 horses for 42/270 days 360 kg of corn would feed 21 horses for (42/270)(360) days 360 kg of corn would feed 21 horses for 56 days
*June 27, 2016*

**Math**

translate from English to Math "If the 16th term of an arithmetic sequence is three times the fourth term" --->a+15d = 3(a+3d) a+15d = 3a+3d 12d = 2a a = 6d term 23 = a+22d = 6d+22d = 28d term 3 = a + 2d = 6d + 2d = 8d term23 : term3 = 28d : 8d = 28 : 8 = 7 : 2
*June 27, 2016*

**Maths**

slope is the same for all line segments = 3 so y = 3x + b plug in one of the points, I will use (1,4) 4 = 3(1) + b b = 1 rule, or the equation is y = 3x + 1
*June 26, 2016*

**Math**

let the number be x (28/5)x = -6/7 196x = -30 x = -30/196 = -15/98
*June 26, 2016*

**math**

let the angle be x its complement is 90-x its supplement is 180-x 7(90-x) = 3(180-x) - 10 solve for x
*June 26, 2016*

**Maths**

In a ||gram, opposite angles are equal, so we have 2x + 25+25 = 360 2x = 310 x = 155 Also not that adjacent angles would be supplementary. Check: 25° + 155° = 180°
*June 26, 2016*

**Algebra**

wind speed ---- x mph speed going with the wind = 160+x speed going against the wind = 160-x 800/(160-x) - 800(160+x) = 3 times (160-x)(160+x) 800(160+x) - 800(160-x) = 3(160+x)(160-x) 800x + 800x = 76800 - 3x^2 3x^2 + 1600x - 76800 = 0 x = (-1600 ± √3481600)/6 x...
*June 25, 2016*

**Math**

2x^2 = 6x 2x^2 - 6x = 0 2x(x - 3) = 0 x = 0 or x = 3 check: if x = 3 2(3)^2 = 18 6(3) = 18 , YUP! if x = 0 2(0) = 0 6(0) = 0 , YUP!
*June 25, 2016*

**geometry**

I would find the length of the lines PQ, PR, and QR then find the lengths of the sides of the other triangle. They should be the same values
*June 25, 2016*

**math**

I just googled "prime numbers" and there are about 18 million results. I am sure you can find the ones in your range.
*June 25, 2016*

**Math HELPPPPP**

x/7+y/11=1 multiply each term by 77, the LCD 11x + 7y = 77 7y = -11x + 77 y = (-11/7)x + 11 the gradient or slope is -11/7 (in your answer you included the variable) b) y+ 5/3x=7/3 , or y = (-5/3)x + 7/3 the slope is -5/3 , so Y=mx+c ----> Y = (-5/3)x + c if (2,3) lies on ...
*June 25, 2016*

**Math**

Two things: --- sin 37° ≠ 6/10 --- there are no "following"
*June 25, 2016*

**Math**

20 hundreds ---> 20(100) or 2000 3 x 10^2 = 300 so what is the difference between 2000 and 300 ?
*June 25, 2016*

**Math**

evaluate: 245612 - (18912 + 45608)
*June 25, 2016*

**Math**

I am a number between 1000000 and 2000000 ---> 1 ??? ??? my hundred thousands, thousands, and ones digits are the same ---> 1 x?x ??x ---> 1 xax bcx My ones digit is the sum of my tens and hundreds digits ---> x = b+c also the sum of my millions and ten thousands ...
*June 25, 2016*

**algebra**

let the initial velocity be k m/s so height = -4.9t^2 + kt d(height)/dt = -9.8t + k when t = 2, d(height)/dt = 0 2 = -9.8(2) + k k = 19.6 so your equation was height = -4.9t^2 + 19.6t the maximum height is = -4.9(4) + 19.6(2) m = appr 19.6 m I used the more traditional ...
*June 24, 2016*

**Pre-Cal**

making a sketch of the situation might help first look at tan^-1 (x/1) construct a right-angled triangle with base angle of Ø, opposite side x, and adjacent side 1 so that tanØ = x/1 r^2 = x^2 + 1^2 r = √(x^1 + 1) sinØ = x/√(x^1 + 1) then csc&...
*June 24, 2016*

**Maths**

9(1/x) = 6(1/17) 9/x = 6/17 6x = 153 x = 153/6 = 51/2
*June 24, 2016*

**math**

Almost impossible to show a "tree diagram" in this format of posting.
*June 24, 2016*

**Math**

see http://www.jiskha.com/display.cgi?id=1466765305
*June 24, 2016*

**Math**

0.0x + .1(40) = .04(x+40) 0.0x + 4 = .04x + 1.6 .04x = 2.4 x = 60 60 ml of water must be added
*June 24, 2016*

**maths**

let the hundreds, tens , and unit digits be x , y, and z respectively . so the original number is 100x + 10y + z the number reversed is 100z + 10y + x 100x + 10y + z - (100z + 10y + x) = 396 99x - 99z = 396 x - z = 4 x = z+4 z - y = y - x 2y = z+x y = (z+x)/2 " if the ...
*June 23, 2016*

**Math**

Just did one like it for Carl. Follow the same steps http://www.jiskha.com/display.cgi?id=1466714995
*June 23, 2016*

**Math**

1 1/3 : 1 3/4 = 4/3 : 7/4 = 16/12 : 21/12 = 16 : 21
*June 23, 2016*

**algebra**

prob(tails and 4) = (1/2)(1/6) = 1/12
*June 23, 2016*

**Math**

I read that as: 1 1/5 / -6 3/7 = a / 4 1/6 (6/5) / (-45/7) = a / (25/6) (6/5)(-7/45) = 6a/25 -14/75 = 6a/25 450a = -350 a = -350/450 = -7/9
*June 23, 2016*

**Math**

length : width = 3 1/3 : 1 5/6 = 10/3 : 11/6 = 20/6 : 11/6 = 20 : 11
*June 23, 2016*

**Algebra**

x-y = 6 x + 2y = 72 subtract them: 3y = 66 y = 22 then x-22 = 6 x = 28 the two numbers are 22 and 28 so "the sum of 3 times the larger and 2" = 3(28) + 2 = 86 You claim your answer is: 192 and 72 Is their difference equal to 6 ????
*June 23, 2016*

**Algebra**

you are missing the rates
*June 23, 2016*

**math**

prob(right) = 1/5 prob(wrong) = 4/5 prob(at least one correct) ----> exclude the case of all wrong prob(all wrong ) = (4/5)^4 prob(at least one right ) = 1 - (4/5)^4 = 369/625
*June 23, 2016*

**math/algebra**

I assume x is the height in feet ? is it T(x) = √x/2 or √(x/2) ?? if will assume the first, t(150) = √150/2 = appr 6.12 seconds If I assumed incorrectly, repeat my steps using the second equation.
*June 23, 2016*

**MATH**

both questions are divisions, 1. Your first question's data makes no sense. 10^-4 million = 1/10^4 million = 1000 The population of the city B = 1000 million = 1 Billion No city has a population of 1 Billion !!!! 2. number of grains of rice = 10^-3 / 10^-9 = 10^6 or 1 ...
*June 23, 2016*

**Math**

so it must look like 5xxx to be as small as possible we need: 5000
*June 23, 2016*

**math**

let the fixed rent be 5x and 3x #1: 100k + 5x = 500 20k + x = 100 #2: 300k + 3x = 1100 100k + x = 1100/3 subtract them: 80k = 1100/3 - 100 = 800/3 k = 10/3 in #1 ----> 20(10/3) + x = 100 x = 100/3 So the difference is the fixed rates = 5x-3x = 2x = 200/3 I was expecting the...
*June 23, 2016*

**math**

x^2+2x-15=(x+r)(x+s) (x+5)(x-3) = (x+r)(x+s) so r = 5 and s = -3 r - s = 5 - (-3) = 8
*June 23, 2016*

**statistics**

cases: one right one right two right three right find prob of each case and add them up I will do one of them: prob(exactly 3 of 13 right) = C(13,3) (1/2)^3 (1/2)^10 = 286(1/2)^13 = 286/8192 = 143/4098
*June 22, 2016*

**Pre-Cal (Help Plz)**

Assuming you are following the convention that a is opposite angle A, etc Sin C/38 = sin28/25 sinC = .71359.. angle C = appr45.5° then angle A = 180-28-45.5 = 106.5° second case: C = 180-45.5 = 134.5° then angle A = 180 - 28 - 134.5 = 17.5° I will leave it up ...
*June 22, 2016*

**trig**

If you make your sketch you will see a cosine law problem. let the distance from port be k nautical miles d^2 = 36^2 + 12^2 - 2(12)(36)cos 150° = ... d = √... = ....
*June 22, 2016*

**math**

so y = (1/3)ax^3 + bx + c points (1,-11) and (2, -16) lie on it, so -11 = (1/3)a + b + c or a + 3b + 3c = -33 ** -16 = (1/3)(a)(8) + 2b + c = 0 8a + 6b + 3c = -48 *** subtract *** from ** 7a + 3b = -15 **** we also know that at (2,-16) , y' = 0 ax^2 + b = 0 at (2,-16) 4a...
*June 21, 2016*

**Math**

I sure hope that doctor is more familiar with the metric system than the question shows A litre (L) is a measure of volume A gram is a measure of mass I sure hope they meant a ml instead of gram so we infuse 1000 ml in 10 hours ---> 100 ml per hour
*June 21, 2016*

**Math1(Please Help Me)**

This applet will be very useful http://davidmlane.com/normal.html You don't even have to find the z-scores, just enter the data as given
*June 21, 2016*

**math**

gibberish! mc023-1.jpg is not an equation, it is a file
*June 21, 2016*

**Maths**

Structured method: Let Ron's age be x Terry is x+25 in 5 years: Ron's age = x+5 Terry's age = x+30 x+30 = 2(x+5) x+30 = 2x+10 20 = x Ron is now 20 and Terry is 45 years old
*June 21, 2016*

**math**

the vote was 5 to 3, so clearly 8 people voted number opposed is 3 of those 8 or 3/8
*June 21, 2016*

**Math**

Can you solve the quadratic: x(2x + 5) = 52 ?
*June 20, 2016*

**Math**

To me that says: x^2 - x = 30 x^2 - x - 30 = 0 (x-6)(x+5) = 0 x = 6 or x = -5 your set is {-5, 6}
*June 20, 2016*

**Algebra**

looks like 4x3x2 or 24 different ways or nPr P(4,3) = 24 you should have that key on your calculator
*June 20, 2016*

**Geometry**

original length -- x original width --- y original height -- z new length ---- x new width ----- y/7 new height --- z/7 original SA = 2xy + 2xz + 2yz new SA = 2x(y/7) + 2x(z/7) + 2(y/7)(z/7) simplify to whatever version you need
*June 20, 2016*

**MATH**

My ones digit is 1 ---- xxx1 My tens digit is 2 ore than my ones digit --- xx31 My thousands digit is the difference when my tens digit is subtracted from my hundreds digit ----> 6931 5831 4731 3631 2531 1431
*June 20, 2016*

**math**

9988 how easy was that ?
*June 20, 2016*

**math**

f(-2) = (-2)^3 + 3(-2)^2 - 2(-2) + 4 = -8 + 12 + 4 + 4 =12 find f(2) and f(0) the same way, then do f(-2) + f(2) - f(0)
*June 20, 2016*

**math**

Easy to figure out by looking at the factors of 20 1x20 2x10 4x5 which have a difference of 8 ?? formal way: let one number be x let the other be x+8 x(x+8) = 20 x^2 + 8x - 20 = 0 (x+10)(x-2) = 0 x = -10 or x = 2 if x = 2, the numbers are 2 and 10 if x = -10, the number are -...
*June 20, 2016*

**Math**

number correct --- x number incorrect --- 20-x 5x -1(20-x) = 70 5x - 20 + x = 70 6x = 90 x = 90/6 = 15 , as Bob stated
*June 19, 2016*

**math**

I assume you want the width of the border. new length = 12+2x new width = 7+2x What has an area of 92 m^2 (you had 92 m) ? if the whole area is 92 m^2 new area = (12+2x)(7+2x) = 92 84 + 38x + 4x^2 = 92 4x^2 + 38x - 8 = 0 2x^2 + 19x - 4 = 0 x = (-19 ± √393)/4 = ....
*June 18, 2016*

**maths**

As long as one of the numbers is even, the product will be even So to have an odd product, all of the factors must be odd to have n consecutive odds is (1/2)^n So to have an even would be 1 - (1/2)^n e.g. suppose we roll it three times, n = 3 according to my formula, prob(even...
*June 18, 2016*

**math**

Most likely the topic is the Sum and Product of roots of a quadratic for ax^2 + bx + c = 0 sum of roots = -b/a product of roots = c/a given: sum of roots = -3+1 = -2 product of roots = -3 then -(a+1) = -2 a = 1 b/1 = -3 b = -3
*June 18, 2016*

**Math**

oil = k(number of buildings)(number of days) o = k bd given: o=6, b=5, d=3 6 = k(15) k = 6/15 = 2/5 oil = (2/5)(bd) 10 = (2/5)(2d) d = 50/4 = 12.5 I agree
*June 17, 2016*

**Algerbra**

area of ||gram = base x height so .....
*June 17, 2016*

**math**

All your choices are correct except the 2nd look at the terms: 7, 21, 63, 189, 567, ... or 7*1, 7*3, 7*9, 7*27, 7*81 looks like 7* 3^(x-1) btw, that sequence is the one that different from all the others, because it is NOT an arithmetic sequence. For the 20th and 100th term, I...
*June 17, 2016*

**Math**

or Just sketch the triangle in II given tanè = -5/1 ----> y/x ---> y = 5, x = -1 r^2 = 5^2+1^1=26 r = √26 sinè = y/r = 5/√26 cosè = -1/√26 tan 2è = 2tanè/(1 - tan^2 è) = -10/(1 - 25) = -10/24 = 5/12
*June 17, 2016*

**Statics**

looks rather straightforward ... (62+62+62+x)/4 = 65 186+x = 260 x = 74
*June 17, 2016*

**If alpha**

You are probably dealing with the properties of the sum and product of roots of quadratic equations. I will use a and b instead of alpha and beta for 2x^2 - 7x + 3 = 0 the sum of the roots = a+b = 7/2 product = ab = 3/2 so the reciprocals of the roots are 1/a and 1/b new sum...
*June 17, 2016*

**Math**

arithmetic sequence with d = 6 and sum of 4 terms = 120 (4/2)(2a + 3d) = 120 2(2a + 18) = 120 2a + 18 = 60 2a = 42 a = 21
*June 17, 2016*

**Math**

let the sides be 4x and 7x 8x + 14x = 7 22x = 7 x = 7/22 then 4x = 4(7/22) = 14/11 cm
*June 17, 2016*

**math**

(4 √3+5√2)/(√48 +√18) = (4 √3+5√2)/(4√3 +3√2) * (4√3 -3√2)(4√3 -3√2) = (48 - 12√6 + 20√3 - 30)/(48 - 18) = (18 + 8√6)/30 do the second one in the same way. multiply top and bottom by 7 + ...
*June 17, 2016*

**math**

a simple way is to find the average of the two numbers for the last one, wouldn't √4 lie between √3 and √5 ? and √4 = 2, so there you have it
*June 17, 2016*