Saturday

October 22, 2016
Total # Posts: 36,333

**Math**

amount in the pail --- x ml amount in the tank ---- 8346 - x ml (8346-x) + 314 = 12(x-314) 8660 - x = 12x - 3768 12428 = 13x x = 956 state conclusion with proper units.

*September 6, 2016*

**math**

number of eggs bought --- x number of eggs sold ----- x-20 4(x-20)/(3x) = 1.2 = 6/5 20x - 400 = 18x 2x = 400 x = 200

*September 6, 2016*

**math**

Since the volume is lwh, and we know h = x+1 then the base is lw = (x^3 + 3x^2 + 2x - 5)/(x+1) = (x^2 + 2x) - 5/(x+1) I had expected the division to be exact. Is there a typo?

*September 6, 2016*

**Math**

Make your sketch. let EC = x , FC = y then (1/2)(x)(y) = 3 xy = 6 area of ABCD = 2x(2y) = 4xy = 24

*September 2, 2016*

**pre calc help please!!!!**

after I took care of your typo x --> x ?? , should be x --> c clearly we just have (5 - 7)^2 = 4

*September 2, 2016*

**math help**

find the direction vector using your two points, then pick one of the points and your direction vector, and follow the method I just showed you in your previous post.

*September 2, 2016*

**math help**

1. x = 1 - t y = -8 + 6t z = -3 - 6t 2. (x-5)/3 = (y+2)/6 = (z+4)/8 did you notice the pattern in the two answers ?

*September 2, 2016*

**math**

weight of cooking oil per litre ---- x kg weight of can ---- y kg 8x + y = 42 3x + y = 27 subtract them 5x = 15 x = 3 sub into 3x + y = 27 9 + y = 27 y = 18 the empty can weighs 18 kg check: 8(3) + 18 = 42 3(3) + 18 = 27 my answer is correct

*September 1, 2016*

**Algebra**

ab - cd will be a maximum if ab is as large as possible and cd is as small as possible I will let d = 1 also we are told that c = a -5, so it is close to a for a maximum of ab, a = b, but our numbers are to be different, and remember that c is only 5 less than a. So we know ...

*September 1, 2016*

**ps12**

7[-7p + 5 + 2(p + 1)] = 6p + 1 7[-7p + 5 + 2p + 2)] = 6p + 1 7[-5p +7] = 6p + 1 -35p + 49 = 6p + 1 -41p = -48 p = 48/41

*September 1, 2016*

**Math**

Think of -n as (-1)(n) so it depends on the value of n if n is positive, then -n is negative. if n is negative, then -n is positive e.g. if n = 5 , -n = -5 , the opposite if n = -5, then -n = -(-5) = +5

*September 1, 2016*

**Algebra**

2x + 1 = x - 2 or 10 - √(6 - x) = 2x - 1 or ....

*September 1, 2016*

**Math**

The LCM, (Least Common Multiple) of 6 and 8 is 24 so you need 24/6 or 4 insects and 24/8 or 3 spiders.

*September 1, 2016*

**Math**

Mary's rate = house/2 Gina's rate = house/3 combined rate = house/2 + house/3 = 5house/6 , (just like 1/2 + 1/3 = 5/6) time at combined rate = house/(5house/6) = house(6)/(5house) = 6/5 notice that "house" canceled, we could have used anything, some would ...

*September 1, 2016*

**maths**

check: amount = 25000(1.08)^2 = 29160 you are correct

*September 1, 2016*

**math**

let the number to be added be x then : (3+x)/(1+x) = (6+x)/(3+x) (1+x)(6+x) = (3+x)(3+x) 6 + 7x + x^2 = 9 + 6x + x^2 x = 3 check: the sequence would then be 4,6, and 9 which is a GP with r = 3/2

*September 1, 2016*

**math**

I assume we are using compound interest. i = .02/12 = .001666... P(1 - 1.001666..^-60)/.001666... = 2000000 I get P = $35055.52 check my arithmetic

*September 1, 2016*

**Math problem soving**

so you are just adding 6 + 12 + 24 + 48 + ... until you get 300 This is the sum of a geometric series with a = 6, and r = 2 sum(n) = a(r^n -1)/(r-1) 300 = 6(2^n -1)/(2-1) 50 = 2^n - 1 2^n = 51 since n has to be a whole number, we can just take a stab at it 2^5 = 32 2^6 = 64 , ...

*September 1, 2016*

**algebriac expression**

second account = d - 3100

*August 31, 2016*

**math**

compare 135/6 with 285/15

*August 31, 2016*

**algebra**

1 cm = 10 mm so L cm = 10L mm be consistent in your spelling, if you use millimetres, then it is also centimetres

*August 31, 2016*

**Math**

7.6×10^6 = 7.6 x 1000000 = ....

*August 31, 2016*

**Boop**

well, you said angle LMN = 6x-20 and angle LMO bisects angle LMN and angle LMO = x+32 so (1/2)(6x-20) = x+32 3x-10 = x+32 2x = 42 x = 21 so angle LMN = 6(21) - 20 = 106 check: then angle LMO = 21+32 = 53 , which is half of 106

*August 31, 2016*

**math**

look at http://www.jiskha.com/display.cgi?id=1472551803 Make any changes necessary. Also consider Steve's method if you have learned about determinants.

*August 31, 2016*

**reiny please help me**

when the tangent line is horizontal, the slope must be zero. But the slope is equal to the derivative, so .... f(x) = 2x^3 + 6x f ' (x) = 6x^2 + 6 then 6x^2 + 6 = 0 6x^2 = -6 x^2 = -1 , good luck on that Since our equation has not real solution, there is no point at which ...

*August 31, 2016*

**math homework**

do we have y = √(x+8) ? I will assume that, if (8,4) lies on it slope = lim ( √(16+h) - 4)/h , as h --->0 multiply top and bottom by (√(16+h) + 4) = lim ( √(16+h) - 4)/h * (√(16+h) + 4)/(√(16+h) + 4) = lim (16 + h - 16)/(h(√(16+h...

*August 31, 2016*

**maths**

Short way: Did you come across this formula yet? distance from a point (a,b,c) to the plane Ax + By + Cz + D = 0 is |Aa + Bb + Cc + D|/√(A^2 + B^2 + C^2) distance = |6 + 10 - 9 + 6|/√(9+4+9) = 13/√22 longer way: parametric equation of perpendicular line from...

*August 31, 2016*

**math**

first equation: m + w = 8000 after discount, price would be .9(8000) = 7200 after VAT, price = 1.1(7200) = 7920 Since I got the final answer without knowing how much the watch or mobile cost, it doesn't matter how much the individual costs. You solution is correct, you can...

*August 31, 2016*

**math**

looks like they played two rounds of the game A's original amount ---- x B's original amount ---- y after first round: A has x+y/4 B has 3y/4 after 2nd round A has x+y/4 - x/3 B has 3y/4 + x/3 ....... You had that, good job, now just have to simplify the equations x+y/...

*August 31, 2016*

**Finance**

So in effect, we want to find the outstanding balance of the mortgage after 8 years. original mortgage = .8(550,000) = 440,000 i = .061/12 = .00508333... P(1 - 1.0050833..^-360)/.00508333.. = 440000 p(165.01792..) = 440000 p = 2666.38 After 8 years, outstanding balance = ...

*August 31, 2016*

**Algebra**

Time taken by the slower train ---- t hrs time taken by faster train --------- t - 1 hrs distance gone by slower train = 40t miles distance gone by faster train = 50(t-1) miles But, when they pass each other, each will have covered the same distance, so 50(t-1) = 40t 50t - 50...

*August 31, 2016*

**algebra**

To answer your question, we would have to know your actual weight, but ... no problem suppose your weight is 130 pounds a) you could lift: 130(1.182 x 10^3) = 153.66 x 10^3 pounds = 153,660 pounds or 1.537 x 10^5 pounds change the solution to match your own weight.

*August 31, 2016*

**math**

Leah, just add them all up, then divide by 44. I am not going to do that simple arithmetic for you. By the way, wouldn't it be spelled metre in Australia ? It is spelled meter only in the US

*August 30, 2016*

**algebra 1**

Use your calculator to find √479 , round to nearest whole number or you know 20x20x = 400 21x21 = 441 22x22 = 484 so what do you think?

*August 30, 2016*

**math**

percent increase = 1000/3000 = 1/3 = ...

*August 30, 2016*

**Calculus**

Make a sketch of the cross-section let the radius be r, let the vertex angle be 2Ø we have a right-angled triangles with angle Ø, opposite is r, and adjacent is 12 tanØ = r/12 12tanØ = r 12 sec^2 Ø (dØ/dt) = dr/dt when r = 6 , ...

*August 30, 2016*

**math homework help**

the major axis lies along the y-axis, so a^2 + 4^2 = 7^2 a^2 = 33 a=√33 x^2/33 + y^2/49 = 1

*August 30, 2016*

**Rainy can you help me with this question?!**

just look at the numbers in the corresponding positions x y 1 9 = 3 5 1 9 so x=3 and y=5

*August 30, 2016*

**math homework help**

If f(x) = 5-2x lim f(x+h) - f(x) / h = lim (5 - 2(x+h) - 5 + 2x)/h = lim (5 - 2x - 2h - 5 + 2x)/h = lim (-2h)/h = -2

*August 30, 2016*

**Maths**

(1/2)x - 1/3 = 4 times 6 , the LCD 3x - 2 = 24 3x = 26 x = 26/3 check: 1/2 of 26/3 = 13/3 difference between 13/3 and 1/3 = 12/3 or 4 we are good here.

*August 30, 2016*

**maths**

I will assume your first equation has a typo, then y = 16-x plug into the 2nd x^2 + (16-x)^2 = 128 2x^2 - 32x +128 = 0 x^2 - 16x + 64 = 0 (x-8)^2 = 0 take over, compare your answer to http://www.wolframalpha.com/input/?i=plot+x%2By%3D16,++x%5E2+%2By%5E2+%3D128

*August 30, 2016*

**math**

Straightforward trig ratio tan Ø = opposite/adjacent tan 40° = height/500 height = 500tan40° = ......

*August 30, 2016*

**calculus**

recall area of parallelogram using vectors u and v = | u X v| go for it, you have u = (-2,1,5) and v = (4,-3,-3)

*August 30, 2016*

**calculus**

if by v * w , you mean v X w , the cross product, then v X w = (5, 8, -1) X (-2, 8, 3) = (32, -13, 56) , I assume you know how to find the cross-product Then u . (v * w) = (5, 9, -6) . (32, -13, 56) = 160 - 117 - 336 = - 293

*August 30, 2016*

**math**

does it look like this ? (9493) ? Are you studying numbers with different bases?

*August 30, 2016*

**math**

What does (94) 93 mean? check your typing.

*August 30, 2016*

**mzumbe**

the difference between 7th and 5th terms is 192 ---> ar^6 - ar^4 = 192 ar^4(r^2 - 1) = 192 ** the difference between 15th and 3rd terms is 48 ---> ar^14 - ar^2 = 48 ar^2(r^12 - 1) = 48 *** divide ** by *** r^2(r^2 - 1)/(r^12 - 1) = 4 **** r^4 - r^2 = 4r^12 - 4 4r^12 - r^...

*August 30, 2016*

**Measurements and applications**

50 mm ----> 4 km 1 mm ------> 4/50 km 75 mm ----> (75)(4/50) km or 6 km ratio = 50 mm : 4 km = 50 mm : 4000000 mm = 1 : 80,000 c) "48squared" km? from your given: (4 km)^2 ---> (50 mm)^ 16 km^2 = 2500 mm^2 1 km^2 = 2500/16 mm^2 48 km^2 = (48)(2500/16) mm^...

*August 30, 2016*

**math**

Use Venn diagrams draw two intersecting circles , one labeled E and the other labeled H within a rectangle. You know the intersection of E and H is 70 and the part outside the two circles is 8 It said 5 failed in H only, so they must have passed E, so they can't be part of...

*August 30, 2016*

**Math**

since (8,6) lies on it, 8/a - 6/b = 1 (8b - 6a)/(ab) = 1 8b - 6a = ab 8b - ab = 6a b(8 - a) = 6a b = 6a/(8-a) ** x/a - y/b = 1 is in the intercept form, that is the x-intercept is (a,0) the y-intercept is (0,b) so the area of the triangle is (1/2)(ab) (1/2)(ab) = 12 ab = 24...

*August 29, 2016*

**Math**

the LCD is 3(3x-9), so let's multiply both sides by that 3(5x+6) = 7(3x-9) this is often called "cross-multiplying" 15x + 18 = 21x - 63 -6x = - 81 x = -81/-6 = 13.5

*August 29, 2016*

**Math**

ambiguous. did you mean the way you typed it, or (5x+6)/(3x-9)=7/3 or 5x+6/(3x) -9=7/3 or .. ?

*August 29, 2016*

**Geometry**

fg = ? but you said fg = 15x-9 check your typing

*August 29, 2016*

**Math**

remember f(x) is just another name for the y value of a function so y = -f(x) means that whatever the y value was of the original function, in - f(x) it is simply the opposite. Thus you have a reflection in the x-axis y = 2 f(x) - 1 we are stretching the y value by a factor of...

*August 29, 2016*

**algebra**

2x - 4 = 22 and 2x - 4 = -22 I assume you know how to solve these

*August 29, 2016*

**Math**

(1/4)g = 16 ---> g = 64 (1/8)b = 7 ---> b = 56 finish it up

*August 29, 2016*

**math**

done, look under Related questions below

*August 29, 2016*

**math**

" .... and ones digits are greater than 10 digits" makes no sense to me

*August 29, 2016*

**Maths**

solve for x .8x = 15

*August 29, 2016*

**math**

hint: from x+y = 16 ----> y = 16-x sub that into the 2nd equation and solve for x using your method of solving quadratics let me know what you get

*August 29, 2016*

**math**

What do you know about the values of a, b, and c in a hyperbola?

*August 29, 2016*

**math**

"and the distance between the centre between F and F, and the semi-ellipse is 5 meters. " ---> confusing, but I think I figured it out Use the properties of an ellipse in terms of its values of a, b, and c c = 14 b = 5 a = ?? In a standard ellipse, a^2 = c^2 + b^2...

*August 29, 2016*

**maths**

length ---- x width = x-4, (it said so) b) perimeter = all the way around = 2x + 2(x-4) = ..... , simplify it c) set your expression from b) equal to 20 and solve for x

*August 29, 2016*

**MATH**

Make a sketch. Think of the plant as a radius of a circle the plant would draw out. Draw in a horizontal to show the lake. At the vertical let OP be the length of the plant, O is the centre and P at the top. then draw a horizontal 6 cm below P so the plant touches at A and B. ...

*August 29, 2016*

**radical equation please help!!!**

your original thinking that sqrt(1+x) -sqrt(1-x) = sqrt (1-x-sqrt(1+x)) is incorrect test it with a value of x e.g. suppose x = .5 then you would have √1.5 - √.5 = √(1 - .5 + √1.5 ) or appr .5176 = appr .455 , not even close What was the rest of the ...

*August 29, 2016*

**math**

1/4 of 48 = 12 1/6 of 48 = 8 1/8 of 48 = 6 so far we counted 26 The remaining 22 must be green

*August 29, 2016*

**math help please?!**

Argghhh, hard to read, besides, you appear to have a typo near the end 1/6 x = 1/8 y - z = -24 -----> 1/6 x + 1/8 y - z = -24 did you mean: 1/3 x + 3/4 y - 2/3 z = -8 x + 1/2 y + 1/3 z = 18 1/6 x + 1/8 y - z = -24 ?? if so , I would clean them up first, 1/3 x + 3/4 y - 2/3 ...

*August 29, 2016*

**math help please?!**

subbing in your values, you will end up with 3 equations, in 3 unknowns #1. 161 = 12a + v + c , I will use c to avoid confusion with a second s #2. 98 = 48a + 2v + c #3. 3 = 108a + 3v + c #3 - #2 ------> 60a + v = -95 #2 - #1 ------> 36a + v = -63 subtract those two ... ...

*August 29, 2016*

**math**

number of pieces --- x she sold 2/3 of them, leaving (1/3)x gave half of that , or (1/6)x to friends, leaving her with (1/6)x but (1/6)x = 6 x = 36 It was cut into 36 pieces

*August 29, 2016*

**math**

Answered when you were Rose

*August 29, 2016*

**Math**

rates of change is the slope of the line the slope of the first line is 2 the slope of the second line is 1/4 The larger the slope, the greater the rate of change, so what do you think?

*August 28, 2016*

**maths**

2 by 2/3 ---> old way of saying 2 divided by 2/3 as in 12 ÷ 3 or 12 by 3 (don' know why they didn't just say 3)

*August 28, 2016*

**Math**

number of people --- x (5/7)x = 540 x = 540(7/5) = ...

*August 27, 2016*

**Little flowers convent school**

So which is it, without leaving any margin, or leaving a margin of 1.5 m all around ? What is the size of the tile ?

*August 27, 2016*

**percentage**

original cost per apple ---- x reduced cost per apple = (2/3)x = 2x/3 75/(2x/3) - 75/x = 25 225/(2x) - 75/x = 25 times 2x 225 - 150 = 50x 50x= 75 x = 75/50 = 1.5 The original price is 1.5 and the reduced price is (2/3)(1.5) = 1 check: at 1.5 Rs, he can buy 75/1.5 or 50 apples ...

*August 27, 2016*

**Math**

40 : 60 : 120 : 140 = 4 : 6 : 12 : 14 = 2 : 3 : 6 : 7

*August 26, 2016*

**value**

from what you have: Logx + logy=4 logx +2logy=3 log(xy) = log(x^4 y^2) = 3 so : log(xy) = log(x^4 y^2) x^4 y^2 = xy x^3 y = 1 y = 1/x^3 , of course x > 0 in logx + logy = 3 logx + log(1/x^3) = 3 log(x(1/x^3)) = 3 log (1/x^2) = 3 1/x^2 = 10^3 = 1000 1000x^2 = 1 x^2 = 1/1000 ...

*August 26, 2016*

**maths reiny help!!**

I just copied my previous solution and changed the numbers: Suppose that the cost of each of the original books was $x per book So the cost was 80x He got a 15% discount, so the cost was (.85)80x = 68x but for 68x he actually got 90 books so the cost of each book was only 68x/...

*August 26, 2016*

**algebra**

width ---- w length ---- w+6 width*length = area w(w+6) = 72 w^2 + 6w - 72 = 0 (w-6)(w+12) = 0 w = 6 or w = a negative the width is 6 cm with only a few nice choices you could have easily checked each one in your head e.g. for the first one: is 10 times 16 equal to 72 ? NO etc

*August 26, 2016*

**Math**

cows --- x chickesn --- y x+y = 12 ** 4x + 2y = 28 or 2x + y = 14 *** subtract ** from *** x = 2 then y = 10 2 cows and 10 chicks

*August 26, 2016*

**math**

2 workers takes 15 hours to make 3 fireplaces 2 workers takes 5 hours to make 1 fireplace 2 workers takes 20 hours to make 4 fireplaces 1 worker takes 40 hours to make 4 fireplaces 5 workers takes 8 hours to make 4 fireplaces or it takes 30 work-hours to make 3 fireplaces it ...

*August 26, 2016*

**Maths**

let Katie's present age be k let Melanie's present age be m Five years ago: Katie ---- k - 5 Melanie -- m-5 k-5 = 10(m-5) k - 10m = -45 ** 2nd condition: Katie's age in 15 years = 3(Melanies age in 11 years) k + 15 = 3(m + 11) k+15 = 3m + 33 k - 3m = 18 *** ...

*August 25, 2016*

**MAth**

I did this for you yesterday http://www.jiskha.com/display.cgi?id=1472041460 Why are you repeating it? btw, it should say "How many complete revolutions are needed?"

*August 25, 2016*

**Math help**

recall that cot^2 x +1 = csc^2 x so ∫(cot^2 x-csc^2 x)^2dx = ∫(cot^2 x-(cot^2 + 1)^2dx = ∫ -1 dx take over

*August 25, 2016*

**MATHS**

what is 1 - .8(.7) ?

*August 25, 2016*

**Math**

add 246 to both sides

*August 24, 2016*

**Math**

correct

*August 24, 2016*

**Math**

Since a constant multiplier is not usually written behind a binomial, I suspect you meant: (x+1)^2 = 9 then x+1 = ±√9 = ±3 x+1 = 3 ----> x = 2 or x+1 = -3 ---> x = -4

*August 24, 2016*

**MAV school**

x/4 + (120-x)/5 = 28 times 20 , the LCD 5x + 4(120-x) = 560 5x + 480 - 4x = 560 x = 80 so we split them up as 80 and 40 , with the 80 being divided by 4 and the 40 divided by 5 check: 80/4 + 40/5 = 20+8 = 28

*August 24, 2016*

**MAth**

Circumference of barrel = 56π cm number of rotations = 2944/(56π) = appr 16.7

*August 24, 2016*

**MATHS PLZZ HELP PLZZ SOMEONE KINDA BEG YOU**

Suppose that the cost of each of the origininal bools was $x per book So the cost was 50x He got a 10% discount, so the cost was (.9)50x = 45x but for 45x he actually got 60 books so the cost of each book was only 45x/60 = 3x/4 As a percentage: (3x/4) / x = 3/4 or 75% which ...

*August 24, 2016*

**math**

The assumption would be that he would be randomly guessing at the answer. Since 12/15 = .8, why did you not include the probability of getting 12 correct out of the 15 ? Try adding that to your other cases. For b) wouldn't getting 20 out of 25 correct yield 80% ? Same for ...

*August 24, 2016*

**Math**

clearly I have a typo in the 3rd last line, should be = 2^2011 (-√3/2 + (1/2) i )

*August 24, 2016*

**Math**

let's use De Moivre's Theorem let z = √3 - 1 sketching it in the Argand plane will give you |r| = 2, and tanØ = -1/√3 Ø = 330° or 11π/6 z = 2(cos 330° - i sin 330°) z^2011 = 2^2011(cos (663630°) - i sin(663630°) ) ...

*August 24, 2016*

**Math**

By "a complete sketch" they very likely want a right-angled triangle. since tanØ = opposite/adjacent = 3/4 and the angle is in the third quadrant y = -3 and x = -4 r^2 = 9 + 16 = 25 r = 5 sin Ø = -4/5 cos(Ø + 180) = cosØcos180 - sinØ...

*August 23, 2016*

**Maths**

circumference of wheel = πd = .98π metres number of rotations = 1540 m/.98π m = 531.898.. = appr 532 rotations how did you get 500?

*August 23, 2016*

**Maths**

I will assume that you meant: (cosecθ-cotθ)^2=(1-cosθ)÷(1+cosθ) or else the identity is not true. LS = (1/sinØ - cosØ/sinØ)2 = (1-cosØ)^2 / sin^2 Ø = (1 - cosØ)(1-cosØ)/( (1 - cosØ)(1 + cos&...

*August 23, 2016*

**math**

What is 1.74 / 0.29 ?

*August 23, 2016*

**Math**

width or breadth ----- x cm length --------------- 3x - 2 solve for x, and sub back into my definitions 2x + 2(3x-2) = 60

*August 23, 2016*

**statistics**

number of "not reds" is 20 so prob(not red) 20/26 = 10/13 or prob(red) = 6/26 = 3/13 prob(not red) = 1 - 3/13 = 10/13

*August 23, 2016*