Sunday

December 4, 2016
Total # Posts: 36,897

**math**

Hard to tell, since you did not define your x I will let Isabella's age be x years then John is 2x - 17 x + 2x-17 = 40 3x = 57 x = 19 So Isabella is 19, but it asked for John's age. John is 2(19) - 17 = 21

*October 2, 2016*

**maths need help**

(a/k)^y=k^m take log of both sides: y(log (a/k) = mlogk y(log a - logk = mlogk yloga = mlogk + ylogk yloga = logk (m+y) logk = yloga/(m+y) also: a^x = k^m xloga = mlogk logk = xloga/m xloga /m = yloga/(m+y) divide by loga x/m = y/(m+y) ym = x(m+y) ym = xm + xy ym - xm = xy m(y...

*October 2, 2016*

**Algebra**

Assuming you meant: 18-4x=6-6x 2x = -12 x = -6 Since we can't see any "following values of x" x = -6 better be part of the list

*October 1, 2016*

**Math**

circumference is a linear measurement, so you can immediately rule out any area or volume. the linear units I see are feet, metres, miles, and kilometres

*October 1, 2016*

**Math**

Only your last question is correct a) at least 2 blue ----> 2 blue, or 3 blue or 4 blue or 5 blue or total - 0 blue - 1 blue number with no restriction = C(19,5) = 11628 number with 0 blue = C(10,5) = 252 number with 1 blue = C(9,1) x C(10,4) = 1890 number with at least 2 ...

*October 1, 2016*

**Math**

I am sure you meant permutations. In a combination, the order does not matter, so there would be only one way For permutation, what is 3 x 2 x 1 ? check by listing them

*October 1, 2016*

**Trigonometry**

You should have learned that the slope of a line is equal to the tangent of the angle that line makes with the x-axis so slope = tan 60° = √3/1 = √3 so the equation is: y - 6 = √3(x - 2) y = √3 x + 6 - 2√3

*October 1, 2016*

**Steve, Damon, bob - differential equations**

The last time I did differential equations was 55 years ago, perhaps one of our other math tutors can kick in here

*October 1, 2016*

**math**

correct, except I would keep the k in the calculation old y = k x^2 new y = k (4x^2) change in y = 3k x^2 percentage change = 3k x^2/(k x^2) = 3 or 300% e.g. enter 1 and 4 for the following applet, http://www.marshu.com/articles/calculate-percentage-increase-decrease-percent-...

*October 1, 2016*

**Probability**

Damon's answer represents the prob of the particular order of AAAKK but it could have been AKAKA, etc that is, we have to multiply his product by 5!/(2!3!) btw, there are 52 cards in a deck, not 54 so his product is 4/52 x 3/51 x .... Once changed to that and multiplied by...

*October 1, 2016*

**math**

The question is not clearly stated. Ms Sue's answer is correct based on that interpretation I will interpret it that you want to know how many different teams of 5 students you can pick e.g. ABCDE would be a different team from ABCDF etc number of possible 5 member teams...

*September 30, 2016*

**mathematics**

first number ---- x second number ---- 2x-1 Their sum = 3x - 1 let's increase it by 2 ----> sum is now 3x + 1 3x+1 = 13 solve for x and all mysteries shall be revealed.

*September 30, 2016*

**math**

250/1200 = ???

*September 30, 2016*

**quadratic functions**

did you sub in your given value of t ? i.e. how about evaluating height = -16(1.5)^2 + 25(1.5) + 6 follow the instructions regarding rounding.

*September 30, 2016*

**English - for Reiny**

I have no idea what that means. Sounds like a Trump-like potpourri of word salad.

*September 30, 2016*

**math**

let the number who play both tennis and badminton be x then 45 = 30+26-x x = 11 badminton only ---> 30-11 = 19 tennis only ------> 26-11 = 15 Illustrate and confirm with a Venn diagram if you need to.

*September 30, 2016*

**calculus help**

I assume you meant: y=(cosxcosy-sinxsiny)/(sinxcosy+cosxsiny) = cos(x+y) / sin(x+y) , using your identities = cot(x+y) dy/dx = - csc^2 (x+y) (1 + dy/dx) dy/dx = -csc^2 (x+y) - dy/dx csc^2 (x+y) dy/dx + dy/dx csc^2 (x+y) = -csc^2 (x+y) dy/dx(1 + csc^2 (x+y) ) = -csc^2 (x+y) dy/...

*September 30, 2016*

**maths**

recall that any multiple of a Pythagorean triple is also a Pythagorean triple I know the "smallest" case is 3-4-5 so using 6 it would be 6-8-10

*September 30, 2016*

**math**

In one hour Kyle can do 1/3 yard In one hour Andres can do 1/4 yard so in 8 hours they can do 8(1/3) + 8(1/4) = 8(1/3 + 1/4) yards = 8( 7/12) yards = 14/3 yards or 4 2/3 yards They can do 14/3 yards (houses) in 8 hours then they can do 14 yards in x hours (14/3) / 14 = 8/x (14...

*September 30, 2016*

**Math**

Assuming you meant: (x+3)(3x^2 - 20x - 7) = 0 (x+3)(x-7)(3x+1) = 0 carry on

*September 30, 2016*

**Math**

common difference = 2k/3 - k = -k/3 given: 20th term is 15 so k + 19(-k/3) = 15 times 3, (I don't like fractions) 3k - 19k = 45 k = - 45/16 first term is -45/16 common difference = -k/3 = 15/16 term 6 = a + 5d = -45/16 + 5(15/16) = 15/8 term n = a + (n-1)d = a + nd - d = -...

*September 30, 2016*

**Algebra**

which property would apply to something like 5 x 6 = 6 x 5 ? I would immediately rule out A and D , since we are NOT adding.

*September 30, 2016*

**Math**

ok, looks like you are saying that you have a box with a square base of r inches each and a height of x inches volume = r^2 x = 78 so x = 78/r^2 cost = 4(area of base) + 3(4 sides) = 4r^2 + 12 rx = 4r^2 + 12(78/r^2)(r) = 4r^2 + 936/r b) makes no sense to me, since the volume ...

*September 30, 2016*

**Math**

original price --- $x after reduced price ---- 89% of x = .8x .8x = 13 solve for x by dividing both sides by .8

*September 30, 2016*

**math**

I don't see the choices you made for this assignment. So how can I check it ?

*September 29, 2016*

**math**

since it is linear, find the slope of the two ordered pairs that you have: assume 2007 ----> t = 0 then for 2012 , t = 5 slope = (28200 - 35250)/(5-0) = -1410 (interpretation: the town loses 1410 each year) so using the point (0,35250) the equation can be written as P = -...

*September 29, 2016*

**Algebra**

Do you like C(L) = .92L better? so the horizontal axis will be labeled L and the vertical axis as C(L)

*September 29, 2016*

**Algebra**

I just paid $11.04 for 12 litres of gas, while last week I paid $$59.80 for 65 litres of gas at the same price. If L is the number of litres, and C is the cost in dollars per L, find the equation for the cost in terms of L So you have 2 points of the form (L,C) and they are (...

*September 29, 2016*

**Statistics**

number of ways to choose first committee = C(18,6) = 18564 that leaves 12 people and we choose 7 of those = C(12,7) = 792 number of ways = 18564*792 = 14,702,688

*September 29, 2016*

**math**

Ok, I agree with your equation of y = (3/2)x + 2 well, if (50,p) lies on it, shouldn't it satisfy your equation? then p = (3/2)(50) + 2 = 75 + 2 = 77 check: http://www.wolframalpha.com/input/?i=plot+%7B(-2,+-1),+(4,+8)+,+(50,+75)%7D

*September 29, 2016*

**math**

amount invested at 6% ---- x amount invested at 8% ---- 3900-x .06x + .08(3900-x) = 280 times 100 6x + 8(3900-x) = 28000 continue

*September 29, 2016*

**Algebra**

width --- x twice the width --- 2x 5 more ----> + 5 5 more than twice the width = 2x + 5

*September 29, 2016*

**Math**

Did you mean: Two consecutive numbers with exact square roots that have a difference of 33 ? since all positive numbers has a square root make a list of perfect squares (they have an exact square root) 1, 4, 9, 25, 36, 64, 81, 100, 121, 144, 169, 196 , 225, 256, 289, .. ahh, ...

*September 29, 2016*

**Math**

by writing it as an exact fraction in the form 57/100

*September 29, 2016*

**Pre-Calculus**

for the first one: sin^2 Ø + cos^2 Ø = 1 divide each term by cos^2 Ø sin^2 Ø/cos^2 Ø + cos^2 Ø/cos^2 Ø = 1/cos^2 Ø tan^2 Ø + 1 = sec^2 Ø, (since 1/cosx = secx) do the 2nd by dividing each term by sin^2 &...

*September 29, 2016*

**Pre-Calculus**

tanØ = 1/2 sketch a right-angled triangle with base angle Ø, opposite as 1 and adjacent as 2 by Pythagoras, the hypotenuse^2 = 1 + 4 = 5 hypotenuse = √5 cosØ = 2/√5 secØ = √5/2

*September 29, 2016*

**maths standard form**

9*10^3 = 9000 So after 9002.05 is reduced by 9000 , we are left with 2.005 or 2 + .005 = 2*10^0 + 5*10^-3 so 9002.005 = 9*10^3+2*10^a+5*10^b = 9*10^3 + 2*10^0 + 5.0*10^-3 a=0 , b = -3

*September 29, 2016*

**Math**

Shiela's original amount --- x Rita's amount = 300-x after give-away: Shiela had x-56 Rita had 300-x + 56 = 356-x 356-x - 5(x-56) 356-x = 5x - 280636 = 6x x = 106 Shiela had $106 and Rita had $194

*September 29, 2016*

**algebra**

speed on first trip --- x km/h speed on return trip --- x-20 let the distance be d time for first part = d/x time for 2nd part = d/(x-20) d/x = 2 ---> d = 2x d/(x-20) = 3 ---> d = 3x - 60 3x-60 = 2x x = 60 So the distance each way was 120 km average speed = 240/5 = 48 km...

*September 29, 2016*

**Algebra 1**

amount = 4000(1.04)^3 I get $ 4499.46

*September 29, 2016*

**Algebra 1**

#1, they double ever 3 hours, so after 3 hours you would have 1000 after 6 hours you would have 2000 after 9 hours you would have 4000 or: number = 500(2^(t/3)) , plug in t = 9 #2, correct #3, 2.01 certainly IS a number between 1 and 10 so C

*September 29, 2016*

**Math**

none of the given choices represent 10/3 in any shape or form

*September 29, 2016*

**MATH HELP!!**

make a sketch to get a "feel" for the triangle a) find the slope of AB, AB, and BC. look for a pair of slopes that are negative reciprocals of each other. If you find such a pair, the the contained angle is your right angle. b) from you sketch you can decide which is...

*September 28, 2016*

**geometry**

umhh, they would have to be equal.

*September 28, 2016*

**maths need help**

nasty, nasty equation. You will have to resort to methods such as Newton's Method to solve simple but tedious and boring way: set your calculator to radians pick some values of x, e.g. let x = 1 LS = 150sin1 = 126.2... RS = 1 + 69.8 = 70.64 , nope let x = .5 LS = 150sin.5...

*September 28, 2016*

**algebra**

-7=11/17z multiply both sides by 17/11 -7(17/11) = (11/17)(17/11)z z = -119/11

*September 28, 2016*

**algebra**

let the distance be d miles time at 90 mph = d/90 time at 80 mph = d/80 d/80 - d/90 = 1 times 720 9d - 8d = 720 d = 720 miles

*September 28, 2016*

**Pre-Calculus**

csc Ø = √5/15 then sinØ = 15/√5 which is greater than 1, thus impossible. error in the question!

*September 27, 2016*

**math**

7d + 4h = 1400 4d + 7h = 1625 use elimination, multiply the first by 7 and the second by 4, the subtract. The h's will drop out I am sure you can handle it.

*September 27, 2016*

**Math**

not enough information. Is the large piece a square? If not, how are the length and width related. e.g. it could be 100 by 10, or 50 by 20, or ....

*September 27, 2016*

**math**

let speed of plane be x mph let the speed of the wind be y mph x+y = 510 x-y = 470 how about adding these two and see what happens.

*September 27, 2016*

**MATH**

no idea what /9 and /5 are supposed to be. I have an inkling you meant √9 and √5 of course √9 = 3, which is an integer.

*September 27, 2016*

**Math**

recall rate = distance / time rate = 90/1.9 ft/s = (90/5280) / (1.9/3600) mph = appr 32.3 mph

*September 27, 2016*

**Pre-Calculus**

cosØ = -√2/2 so Ø is in quadrants II or III you should know the trig ratios of the 45-45-90 as well as the 30-60-90 degree triangles. so you know the angle in standard position is 45°, because cos45 = √2/2 so Ø = 180-45 or 135° (in II) ...

*September 27, 2016*

**Math~ Algebra 1**

key concept: both would have covered the same distance let time of first car until catchup be t hrs let time of 2nd car until they meet be t-1 hrs 55(t-1) = 44t 55t - 55 = 44t 11t = 55 t = 5 distance = 5(44) or 4(55), same thing, = 220 miles

*September 27, 2016*

**Pre-Calculus**

csc Ø = 1.03 then sin Ø = 1/1.03 = appr .970873... make sure your calculator is set to radians Ø = 1.33 or π-1.33 = 1.8127 (in degrees, Ø = 76.14° or 103.86° ) Why were you unable to do that?

*September 27, 2016*

**Math**

7^-10 = 1/7^10 = ...

*September 27, 2016*

**Math**

the number is 4XX, 3XX, 2XX, 1XX or AB --- the number is a multiple of 6 multiples of 6 end in 6, 2, 8, 4, and 0 but it is NOT a multiple of 5, so that rules out the 0 ---- the tens digit is double the ones digit that rules out the 6 and 8 from the ones digit so the one's ...

*September 27, 2016*

**brain teaser**

number of sweaters ---- x number of skirts ------- y 3x + 2y = 3y 3x = y or x = y/3 so she has 3y to spend if she buys 1 skirt, or she spends y, that leaves her with 2y but y = 3x, so 2y = 6x = 6 sweaters check: suppose she has $90 so she can buy 3 skirts, each skirt would ...

*September 27, 2016*

**Counting and Probability**

Which 2 girls? Any two girls ? Can 3 girls or more sit beside each other, or only 2 girls? The wording is not specific enough. I will assume that we are talking about 2 specific girls, and instead of 9 chairs we have to arrange them in 8 ways. number of ways = 8! (suppose the ...

*September 27, 2016*

**Math**

a = 5 v = 5t + c when t = 0, v = 20 20 = 0+c ---> c = 20 then v = 5t + 20 when s is the distance, s = (5/2)t^2 + 20t + k when t = 0, s = 0 0 = 0 + 0 + k ---> k = 0 s = (5/2)t^2 + 20t how long did it take to go 10 m ? 10 = (5/2)t^2 + 20t 20 = 5t^2 + 40t t^2 + 8t = 5 I ...

*September 27, 2016*

**maths**

Just translate .... "pole C is 260 cm shorter than pole A" C = A - 260 but pole C = 1040 1040 = A-260 A = 1300 "pole A is twice as long as pole B" A = 2B 1300 = 2B B = 650 Now just add them up

*September 27, 2016*

**math**

In a parallogram, any two adjacent angles must add up to 180° so x + x+30 = 180 continue ....

*September 27, 2016*

**Math**

each brick has a volume of (6)(3)(2) inches^3 or 36 cubic inches so 1800 bricks would be 64,800 cubic inches you did not specify which units, so 1 cubic foot = 12^3 or 1728 cubic ft 1 cubic yard = 27 cubic ft use the above to convert to whichever units you need.

*September 27, 2016*

**math**

4.75 , I see 2 decimal places, so .. = 475/100 = 19/4

*September 27, 2016*

**Maths**

did you mean, find the number of subsets ? if so, there would be 2^5 or 32 of them, including the null set and the entire set

*September 27, 2016*

**Maths**

number that passed chemistry --- c number that passed biology ------ b sketch a Venn diagram, label the circles C and B place 8 in the intersection of the two circles place b-8 and c-8 in the parts of the circle not overlapping. so b-8 + 8 + c-8 = 60 b+c = 68 but it said: b = ...

*September 27, 2016*

**Math**

I don't understand. Didn't you state that the value of x is 75 ?

*September 27, 2016*

**Math**

how about 233 or 4211 or 2222 or 111,122 or ..

*September 26, 2016*

**maths quartic equation need help**

I just divided the quadratic that Steve found into the origianl quartic and got x^2 + 4x + 3 which factors to (x+1)(x+3) So the other two roots are -1 and -3

*September 26, 2016*

**maths**

total surface area = 2(7.2)(5) + 2(7.2)(3.32) + 2(5)(3.32) why are you using both a "," and a "." to represent the decimal place?

*September 26, 2016*

**Trigonometry**

Let the sides of triangle ABC be a, b, and c ,so that a is opposite angle A, etc we know a+b+c = 52, so c = 52-a-b sinA/sinB = a/b a/b = 3/4 4a = 3b---> b = 4a/3 sinA/sinC = a/c 3/6 = a/(52-b-a) 1/2 = a/(52-a-b) 2a = 52 - a - b 3a = 52-b 3a = 52 - 4a/3 9a = 156 - 4a 13a = ...

*September 26, 2016*

**Algebra**

your function will look like this: population = 56 e^kt, where t = 0 represents 1995 then 2002 ---> t = 7 and 2016 ---> t = 21 for t = 7 (2002) 59 = 56 e^7k 1.05357... = e^7k 7k = ln 1.05357.. = .052185753 k = appr .0074551 pop = 56 e^(.0074551t) sub in t = 21 and evaluate

*September 26, 2016*

**math**

You should first of all define x. If x is the amount left to be spent, then x+15 ≤ 60

*September 26, 2016*

**math**

cost price per apple = 1.2 they sold 70 at 1.5 or return = 105 profit = 5 percentage profit = 5/100 = .05 = 5%

*September 26, 2016*

**Math**

Traditionally, a line segment can be labeled by using the end points, such as AB where A is one end point and B is another If the direction you are going does not matter, AB would be the same as BA If direction is involved, we have something called a vector, but I don't ...

*September 26, 2016*

**Math**

376 , 377 , 378 ?? both 376 and 378 are multiples of 2

*September 26, 2016*

**Math**

my solution: let the other end point be (x,y) to get the x: (x+3)/2 = 5 x+3 = 10 x = 7 to get the y: (y+5)/2 = -11 x+5 = -22 y = -27 You had that, good job I agree, your teacher is in error.

*September 26, 2016*

**Math**

CD = 7-(-9) = 16 , or count them CE = (5/8)(16) = 10 now count over 10 units from C E ---> -9 + 10 = 1

*September 26, 2016*

**Math**

multiply the first by 3: 12x+9y=45 keep the 2nd 7x+9y=75 subtract them , (here is your elimination method) 5x = -30 x = -6 sub that back into the original 1st -24 + 3y = 15 3y = 39 y = 13 x = -6, y = 13

*September 26, 2016*

**Math**

I think you are having difficulty understanding the meaning of modular arithmetic I will use an example e.g. what is 15 mod 12 Think of a clock, after we have gone around counting the hours 1,2,3,... etc we start over again after 12 hours so it becomes obvious that 15mod12 = 3...

*September 26, 2016*

**Algebra**

clearly 7 x 10 or 70 tiles. Can you explain how I got that?

*September 26, 2016*

**ALgebra**

ages three years ago: Erna --- x Wendy --- 3x/4 Lucy ----- 2x/3 their ages now: Erna --- x + 3 Wendy --- 3x/4 + 3 Lucy ----- 2x/3 + 3 x + 3 + 3x/4 + 3 + 2x/3 + 3 = 67 x + 3x/4 + 2x/3 = 58 times 12, the LCD 12x + 9x + 8x = 696 x = 24 plug into my present age definitions.

*September 26, 2016*

**Math**

5 years ago: Lyn ---- x Anne -- 5x Now: Lyn = x+5 Anne = 5x+5 10 years from now: Lyn = x+15 Anne = 5x + 15 x+5 = (1/2)(5x + 15) 2x + 10 = 5x + 15 -3x = 5 solution makes no sense, the question is bogus.

*September 26, 2016*

**math**

total session including lunch = 13:00 - 9:30 = 4:00 session excluding lunch = 4:00 - .45 = 3:60 - 45 = 3:15 or 3 hours and 15 minutes

*September 26, 2016*

**Math Need Help**

why complicate things? wouldn't that just be ∫(4/(4-5x))dx = 4∫(1/(4-5x))dx = 4(-1/5) ln(4-5x) + c = (-4/5) ln(4-5x) + c

*September 26, 2016*

**Math**

do one step of a long division to get (x^2)/(x^2+1) = 1 - 1/(x^2+1) ∫(x^2)/(x^2+1)dx = ∫( 1 - 1/(x^2+1))dx = x - tan^-1 (x) + c , the last part should be part of your repertoire of integrals

*September 26, 2016*

**Calculus**

limit of (x^2 - 25)/(x^2 - 4x - 5) , as x --> 0 = lim(x+5)(x-5)/( (x-5)(x+1) = lim (x+5)/(x+1) , as x ---> 0 = 5/1 = 5

*September 25, 2016*

**math**

you will find this page perfectly suitable for your question http://davidmlane.com/normal.html

*September 25, 2016*

**Math**

No, one of your slopes is incorrect #3: 4x - y = 9 --> 4x - 9 = y , so the slope is 4 sum of slopes = -2 + 6 + 4 = 8

*September 25, 2016*

**algebra**

y=4x - 2 switch the variables x = 4y - 2 solve this for y 4y = x + 2 y = (x+2)/4 f^-1 (x) = (x+2)/4

*September 25, 2016*

**algebra**

g(6) = 3(6) - 5 = ...

*September 25, 2016*

**Math**

5 7/8 - 1/4 = 47/8 - 2/8 = 45/8 or 5 5/8

*September 25, 2016*

**Absolute Inequalities**

4-|2x-3| ≤ 9 -|2x-3| ≤ 5 |2x-3| ≥ -5 or by default: |2x-3| ≥ 0 , since the absolute value of anything ≥ 0 2x-3 ≥ 0 OR -2x+3 ≥ 0 x ≥ 3/2 OR -2x ≥ -3 x ≤ 3/2 so any value of x will work the solution is the set of real ...

*September 25, 2016*

**Algebra 2**

how about just subtracting 6y from both sides. See what your equation looks like. After that, I would also divide each term by 3 You should be able to do this in your head.

*September 25, 2016*

**Urgent Math**

let's take a look what we are dealing with http://www.wolframalpha.com/input/?i=plot+y+%3D-x%5E2+%2B+4x+%2B3+,+y+%3D+-x%5E3+%2B7x%5E2-10x+%2B+5 We can see that within your domain of 1 ≤x≤2 , they do not cross each other. so the effective height of our region...

*September 25, 2016*

**correction - Math**

since the tiles are 2 ft by 2 ft, and the room is 11 ft along one side, you will need 6 tiles along that side, with the last one to be cut along the 12 ft length, 6 tiles will fit, so you will need 36 tiles.

*September 25, 2016*

**math**

12 ft ÷ 7.5 inches = 144 inches ÷ 7.5 inches = 19.2 steps but the number of steps is a whole number. if we have 19 steps each would be 144/19 or 7.598 inches high, which is too high so we have to go with 20 steps, each one 7.2 inches high

*September 25, 2016*

**math**

What is a tossed altitude ? I will assume the question is as follows: Triangle ABC, AB = 15 , AC = 18 AD is an altitude where D is on BC and BD = 10 BD^2 + 10^2 = 15^2 BD = √125 = 5√5 similarly, CD = √224 = 4√14 BC = appr 26.147 cm Let the altitude from...

*September 25, 2016*

**MATH 6grade**

I now count 11 "Juan and his bookcase" questions. I don't think Juan will ever get it build.

*September 25, 2016*