Friday

September 30, 2016
Total # Posts: 36,074

**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*

**Calculus**

Your 3 strips would be 3 trapezoids. The confusing part is the fact that the last "trapezoid" is actually just a triangle area of trapezoids = (1/2)(1)(6+4) + (1/2)(1)(4+2) + (1/2)(1)(2+0) = 5 + 3 + 1 = 9 ( your area consists of a triangle with a base of 3 and a ...

*June 17, 2016*

**math**

I would use a common denominator of 36 take it from there

*June 17, 2016*

**Calculus**

If you meant lim x-->0 ((7-3x^5+(x^2)(sinx) )/(5cosx)) then you are right If you meant: lim x-->0 ((7-3x^5+x^(2sinx) )/(5cosx)) I got 8/5

*June 17, 2016*

**calculus**

Forget about limits for a while and just consider the simple facts: f(x) = 5 starts at -2 and goes to the left then f(x) = -5 starts at 3 and goes to the right. Those two lines are "linked" by a straight line from (-2,5) to (3,-5) Let's just find that line ..... ...

*June 17, 2016*

**math**

if 1 ft corresponds with 1/8 inch then 15 ft correspond with 15(1/8) inches = 15/8 inches or 1 7/8 inches

*June 17, 2016*

**algebra**

prob(red) = 12/15 = 4/5 prob(not red) = 1/5 prob( 7 reds of 10) = C(10,7)(4/5)^7 (1/5)^3 = appr .2013

*June 16, 2016*

**Math10**

a+3d = 18 a+5d = 28 subtract them: 2d = 10 d = 5 a + 15 = 18 a = 3 now form the first 3 terms

*June 16, 2016*

**geometry**

full volume = 14(16)(10) inches^3 = 2240 inches^3 amount which is empty = 2240-1680 = 560 inches^3 percent empty = 560/2240 = .25 or 25% empty

*June 16, 2016*

**Algebra**

let the time taken by the robber when he is caught be t hrs distance he covered = 12t miles time taken by the marshall to catch him = t - 1/3 distance traveled by him = 16(t - 1/2) but 12t = 16(t - 1/2) 12t = 16t - 16/2 -3t = -16/2 t = 8/3 hrs

*June 15, 2016*

**Frederick**

let each side of one square be x cm let the other have side length y cm so we know: x^2 + y^2 = 100 *** and 4x + 4y = 50 2x+2y=25 ** y = (25-2x)/2 subbing the 2nd part into the first: x^2 + (625 - 100x + 4x^2)/4 = 100 times 4 4x^2 + 625 - 100x + 4x^2 = 400 8x^2 - 100x + 225 = ...

*June 15, 2016*

**Math**

Volume = area of base x height 210 = 42 h h = 5 Of course there is an infinite number of possible dimensions. If we are restricted to whole numbers, possible cases could be 6 x 7 x 5 , or 2 x 21 x 5, or 3 x 14 x 5, or 1 x 42 x 5 or 1 x 1 x 210 , or 7 x 3 x 10 , or .....

*June 15, 2016*

**Math**

So the angles are x, x, 2x, 3x, 3x, 90 and the sum of all 6 angles in a hexagon is 720 can you take it from here ?

*June 14, 2016*

**math**

I assume you are dealing with an AS a+4d + a+23d = 50 2a + 27d = 50 sum of first and 28th = a + a+27d = 2a + 27d = 50 28th term = a + 27d = 50 - a

*June 14, 2016*

**maths**

Since the common formula for the amount of an annuity : amount = Payment( (1+i)^n - 1)/i is base on the fact that the payment is made at the end of the period, the only twist that I see in the question would be the first month and the last month. I will also assume that the ...

*June 14, 2016*

**maths**

I will use the fact that she deposits $M for the entire period plus and addition $M for the last 15 years, (making it 2M for the last 15 years) i = .06/12 = .005 M(1.005)^480 - 1)/.005 + M(1.005)^180 - 1)/.005 = 1000000 M( 1.005^480 -1 + 1.005^180 - 1)/.005 = 1000000 I get M...

*June 14, 2016*

**math**

x(1.05) = 300 x = 300/1.05 = $285.71 What is the meaning of the (2%) ?

*June 14, 2016*

**Business Math**

i = .07/12 = .0058333... n = ? 1(1.005833..)^n = 2 log both sides n log 1.005833.. = log 2 n = log 2/log 1.0058333... = 119.17.. months = appr 9 years and 11 months

*June 14, 2016*

**math**

I will assume that the second rate was also compounded quarterly quarterly rate for first 5 years = .06/4 = .015 quarterly rate for last 5 years = .045/4 = .01125 amount after first 5 years = 5000(1.015)^20 and after the last 5 years = 5000(1.015)^20 (1.01125)^20 = $8422.90

*June 14, 2016*

**Algebra**

A line perpendicular to 7x - 6y = 30 must look like 6x + 7y = c how do you think we can find c ?

*June 13, 2016*

**algebra**

Just use the formula, surely you have that in your textbook or your notes.

*June 13, 2016*

**Calculus**

Wow, nice problem with very clear and precise instructions how to do it. I suggest you just follow the steps they ask you to perform. I will start you off. Let the finished box be x inches long, y inches wide and 3 inches high given: 3xy = 2760 xy = 920 original piece is (x+6...

*June 13, 2016*

**math**

cone = (1/3)π r^2 h where r = 1.5 h = 12 find the volume of the cone, just plug in the values Can = π r^2 h r = 2 h = 2 volume of can = ..... compare to see which is larger. take the difference to see which hold more

*June 13, 2016*

**Math**

Let AC = x let AB = 2x We can use the cosine law to find x x^2 + (2x)^2 - 2(x)(2x)cos120° = 8^2 5x^2 - 4x^2(-1/2) = 64 7x^2 = 64 x^2 = 64/7 x = 8/√7 perimeter = x+2x+8 = 3x + 8 = 24/√7 + 8 = appr 17

*June 13, 2016*

**Algebra**

I think they want the equation in the form ax^2 + bx + c = 0, where a is a positive real number so just "move" all the terms to the left side and set them equal to zero e.g. #5 4x + 3 = x^2 -x^2 + 4x + 3 = 0 x^2 - 4z - 3 = 0 Do the others the same way, it is really ...

*June 11, 2016*

**College Algebra II**

The midpoint of (a,b) and (c,d) is ( (a+c)/2 , (b+d)/2) ) let P2 be (c,d) for the x value : (c + (-2) )/2 = -1 c -2 = -2 c = 0 find the y value of P2 in the same way. Check by finding the midpoint of P1 and P2 using the formula I gave, and make sure you get the point (-1,3)

*June 11, 2016*

**Math**

A = {2,3,5} and B = {1, 3, 5} 2+1 = 2+3 = 2 + 5 = 3+1 = 3+3 = 3+5 = 5+1 = 5+3 = already have that 5+5 = make sure you don't count equal sums twice, e.g. 3+3 = 6 5+1 = 6 You are just looking at the different sums

*June 11, 2016*

**Math**

no in a phase shift, the shape of the sine curve does not change, but in a period change you are changing the shape

*June 11, 2016*

**Math**

Did you mean that 3 of the angles are in the ratio of 2:3:7 ? let those three angles be 2x, 3x, and 7x let the fourth angle be y 2x + 3x + 7x + y = 360 y + 12x = 360 y = 360 - 12x "the mean of these angles is 64" I will assume you mean the mean of the 3 angles. 12x/3...

*June 11, 2016*

**Math**

x^2 + 13x - 30 = 0 (x-2)(x+15) = 0 x = 2 or x = -15 which is the smaller ?

*June 11, 2016*

**Math**

original fraction: x/(x+4) new fraction = (x+3)/(x+7) (x+3)/(x+7) = 3/4 4(x+3) = 3(x+7) solve for x, and sub back into original fraction

*June 11, 2016*

**math**

ummmh, so the sum is 18 made of 6 equal digits?? What do you think?

*June 11, 2016*

**algebra**

Just stating the answer is not helping Tourille learning how to do this.

*June 11, 2016*

**Calculus**

Let one of them be x, and the other one y xy = 2 y = 2/x sum = x+y = x + 2/x d(sum)/dx = 1 - 2/x^2 = 0 for a min sum 1 = 2/x^2 x^2 = 2 x = √2 , then y = 2/√2 = √2 their minimum sum = x+y = √2 + √2 = 2√2

*June 10, 2016*

**Math**

tried to find a relation, could not find a definite one. the graph looks almost linear. http://www.wolframalpha.com/input/?i=pattern(100,+105,107,110,+115,120,123,126) (I used units of 1000) What is your depth of study of this? Have you learned about "equations or lines ...

*June 10, 2016*

**Math**

What are we finding? The equation? let y = kx for the given values: 3 = 7k k = 3/7 so y = (3/7)x or x = (7/3)y or y/x = 3/7 or y : x = 3 : 7 etc

*June 10, 2016*