Monday

December 5, 2016
Total # Posts: 36,897

**PreCal**

b = -(4-√3) = (-4 + √3) then b^2 = 16 - 8√3 + 3 = 19 - 8√3 Bob had 15-8√3 for that part modify his solution.

*October 28, 2016*

**macomb**

You have no exponents in your original question. Ms Sue's answer is correct for the question you typed. did you mean −8^−1 + 8^−2 ? then = 1/-8 + 1/8^2

*October 28, 2016*

**Algebra**

You did not post the sequence

*October 28, 2016*

**math**

A = 2 pi r (r+h) A = 2π r^2 + 2πrh A - 2πr^2 = 2πrh h = (A - 2πr^2)/(2πr)

*October 28, 2016*

**math**

You probably meant to type: y = (2x^2 - 5)/(3x^2 - 4) ok, what about it?

*October 28, 2016*

**Math**

I have no idea how you got .1446.. 12% ---> 0.12 17% ---> 0.17 3% ---> 0.03 add them up to get 0.32

*October 28, 2016*

**Math**

area = 4(2/3) ft^2 = 8/3 ft^2

*October 28, 2016*

**Math**

Both the first and the third are given in terms of the 2nd, so we will let the second be our base variable let the 2nd be x then the first is 3x and the third is 10x 10x - 3x = 1050 7x = 1050 x = 150 sub back into my definitions and add them up

*October 27, 2016*

**Math**

Ms Sue's answer is the correct one.

*October 26, 2016*

**Differential calculus**

y=(√e^x)/x y = (e^(x/2) )/x dy/dx = (x(1/2)e^(x/2) - e^(x/2) )/x^2 simplify if needed.

*October 26, 2016*

**Differential calculus**

what kind of root? square root ? is it √(e^x/x) or (√e^x) / x ?

*October 26, 2016*

**Differential calculus with analytic geometry**

xy^2+4y^3=x-2y x(2y)dy/x + y^2 + 12y^2 dy/dx = 1 - 2dy/dx dy/x(2xy + 12y^2 + 2) = 1 - y^2 dy/dx = (1 - y^2)/(2xy + 12y^2 + 2)

*October 26, 2016*

**Math**

Use a Venn diagram, put in all the data values, and your answers can just be read from the diagram

*October 26, 2016*

**Calculus**

2x^2y-3y^2=-11 4xy + 2x^2 dy/dx - 6y dy/dx = 0 dy/dx(2x^2 - 6y) = -4xy dy/dx = -4xy/(2x^2 - 6y) at (2,-1) dy/dx = -4(2)(-1)/(8 -6(-1)) = 8/14 = 4/7 equation of tangent: y+1 = (4/7)(x - 2) massage it any way you need to

*October 26, 2016*

**Algrebra**

To visualize the different cases, why not give yourself an actual point. e.g. 2) let (x,y) = (-4,5) <---- had to be in quadrant II then (-x,y) = (4,5) , which is in first quadrant (x,-y) = (-4,-5) , in the third (-x,-y) = (4,-5) , in the fourth

*October 25, 2016*

**Algebra**

number of tens ---- x number of fives ---- x+2 number of twenties -- 2x-3 value equation: 10x + 5(x+2) + 20(2x-3) = 445 10x + 5x + 10 + 40x - 60 = 445 55x = 495 x = 9 sub into my definitions ...

*October 25, 2016*

**Math**

each side of the base ---- x ft height of box ------------ y ft x^2 y = 8 y = 8/x^2 cost = 6x^2 + 4xy = 6x^2 + 4x(8/x^2) cost = 6x^2 + 32/x

*October 25, 2016*

**Algebra**

second number ----- x first number ------- 2x - 183 solve for x: x + 2x-183 = 1161

*October 25, 2016*

**Math**

let the longer piece be x cm then the shorter piece is 14-x cm 14-x = (2/5)x times 5 70 - 5x = 2x 70 = 7x x = 10 the long piece is 10 cm, the shorter is 4 cm check: is 4/10 = 2/5 ? , YES

*October 25, 2016*

**math**

Most direct way: The volume of the rock equals the change in the volume of the tank. The change in the height was 4 cm. So the volume of the rock is (9)(15)(4) cm^3 = 540 cm^3 or, along your thinking volume of tank at the start = (9)(15)(8) or 1080 cm^3 volume after rock is ...

*October 25, 2016*

**math**

I have no idea what your x and y stand for, but in a rhombus, opposite angles are equal and adjacent angles add up to 180° So the other angle is 130°

*October 25, 2016*

**Math**

assuming 30 days in a month ... cost of one can per day from machine = 30(.75) = $22.50 cost using 12-pack = (4.99/12)(30) = 12.48 continue

*October 25, 2016*

**Algebra 1**

1. A - wrong 2. C - wrong 3. B - wrong 4. A - wrong How did you get your answers? Where you just guessing?

*October 25, 2016*

**Algebra 1**

I don't see any choices or any work Surely you don't expect somebody to just go ahead and do this assignment for you , do you? e.g. what steps would you take to answer the first one?

*October 25, 2016*

**Mathematics**

Just use your definitions: "first term of an Arithmetic Progression is -4" --> a=-4 "the 15th term is double the 5th" ---> a+14d = 2(a+4d) a + 14d = 2a + 8d 6d = a 6d = -4 d = -2/3 term 12 = a + 11d = -4 + 11(-2/3) = -25/3 check: is the 15th term ...

*October 25, 2016*

**Algebra Two**

2500 + .06s ≥ 3100 , where s is his sales .06s ≥ 600 s ≥ 600/.06 s ≥ 10,000

*October 25, 2016*

**Maths GRE**

correct

*October 25, 2016*

**Maths GRE**

correct , so D

*October 25, 2016*

**Math**

fathers age ---- 8x son's age ----- 3x but 8x = 48 x = 6 so the son is 18 or , just using a ratio .... 48/s = 8/3 8s = 144 s = 144/8 =18

*October 25, 2016*

**math**

If PQ = QR , (where P(6,-1), Q(1,3), R(x,8)) √( (3+1)^2 + (1-6)^2) = √( (8-3)^2 + (x-1)^2 ) √41 = √(x^2 - 2x + 26) square both sides 41 = x^2 - 2x + 26 x^2 - 2x - 15 = 0 (x-5)(x+3) = 0 x = 5 or x = -3

*October 25, 2016*

**Math**

average hourly change = (-21 - 63)/12 degrees/hr =

*October 25, 2016*

**maths**

http://www.jiskha.com/display.cgi?id=1477323150

*October 24, 2016*

**maths**

http://www.jiskha.com/display.cgi?id=1477323001

*October 24, 2016*

**maths**

I did this for you when you were Saphina AlMatary http://www.jiskha.com/display.cgi?id=1477322557 I gave you a good hint for the second one Did you even look at it?

*October 24, 2016*

**Math**

good call Steve! (at least I got the right answer, lol)

*October 24, 2016*

**Math**

The largest angle will be opposite the side 28 let it be 2Ø, so each bisected angle is Ø let the bisector form angles A and B along the 28 side, so that A + B = 180° --> B = 180-A and we know sinA = sin(180-A) = sinB let the 28 side be split into x and 28-...

*October 24, 2016*

**maths**

To talk about "roots" you need equations, you don't have any. anyway.... for 3x^2 - 6x - 7 = 0 , the sum of the roots is 6/2 or 3 and the product of the roots is -7/3

*October 24, 2016*

**maths**

check in your text or in your notes what properties are needed to investigate the nature of the roots. hint: it has to do with the determinant. btw. - I can't make your your last equation.

*October 24, 2016*

**Math**

clear case of the cosine law BC^2 = 4^2 + (3√3)^2 - 2(4)(3√3)cos30° carry on

*October 24, 2016*

**maths**

There is no unique or best way to solve these. After doing a few you get a "feel" of what to look for. e.g. for your first one, notice that last one says: y - 4z = 25 , so y = 25+4z - could be useful look at the first two, they both have 1x so lets subtract the 2nd ...

*October 24, 2016*

**Math**

What is your question? What does "and three points at the time of closing" mean?

*October 24, 2016*

**maths**

-did the first one for you - still waiting for your response to the second part of my reply http://www.jiskha.com/display.cgi?id=1477316621

*October 24, 2016*

**Math Check Answers**

both are correct

*October 24, 2016*

**correction- math**

Sara found the area. You want the perimeter = 2(12.75) + 2(8.25) = ..

*October 24, 2016*

**maths**

hard to tell which are your groups of equations.

*October 24, 2016*

**Math Check Answers**

answers: #1 - A #2 - D #3 - B

*October 24, 2016*

**maths**

x^2 - 6x = x^2 - 6x + 9 - 9 = (x-3)^2 - 9 3x^2 + 20x = 3(x^2 + (20/3)x + 100/9 - 100/9 = 3( (x + 10/3)^2 - 100/9 = 3(x+10/3)^2 - 100/3

*October 24, 2016*

**maths**

If the coefficient of x^2 is 1, look for 2 numbers which when multiplied give you the constant, and which when added give you the coefficient of the middle term that is, (-10)(4) = -40 (-10) + 4 = -6 so (x - 10)(x + 4) for the second one: 3x^2 + 20x - 7 = 0 , what method have ...

*October 24, 2016*

**Math**

make a sketch. split the figure into a rectangle and a right-angled triangle. in the triangle the base will be 21-13 or 8 cm and the hypotenuse is 17 let the height be h h^2 + 8^2 = 17^2 h^2 = 225 h = 15 area = rectangle + triangle = 13(15) cm^2 + (1/2)(8)(15) = 255 cm^2

*October 24, 2016*

**math**

to be divisible by 6, it must be divisible by 2 AND 3 8454 is even, so it is divisible by 2 the sum of the digits of 8454 is 21, which is divisible by 3, so 8454 is divisible by 3 (divisibility test for 3: if the sum of the digits of any number is divisible by 3, so is the ...

*October 24, 2016*

**Math**

What is C(4,3) ?

*October 24, 2016*

**Math**

π is indeed an irrational number , but Don Ho said π = 3.14, which is not true, since 3.14 = 314/100 or 157/50 and that would be a rational number all radicals that are not perfect squares, are also irrational number e.g. √5

*October 24, 2016*

**MATH**

You will need brackets in 6/(3-x) = (7-5x)/6 and (3-x)(7-5x) = 36 21 -22x + 5x^2 = 36 5x^2 - 22x - 15 = 0 (x - 5)(5x + 3) = 0 x = 5 or x = -3/5 the common ratio is 6/(3-x) if x =5, common ratio is 6/-2 or -3 if x = -3/5, common ratio is 6/(3 + 3/5) or 5/3

*October 24, 2016*

**maths**

I will assume this is an arithmetic sequence. Let's just use our formulas we know d = 2 sum(10) = 93 ---> n = 10, a = ? (10/2)(2a + 9(2)) = 93 5(2a + 18) = 93 10a + 90 = 93 10a = 3 a = .3 check: 10th term = a+9d = .3 + 18 = 18.3 sum(10) = (10/2)(first + last) = 5(.3+18....

*October 23, 2016*

**maths percentage**

You appear to have a typo ---- 3205% ????

*October 23, 2016*

**maths need help too hard**

4^x+3^x=9^x 4^x+3^x=3^(2x) 4^x = 3^(2x) - 3^x) 4^x = 3^x(3^x - 1 (4/3)^x = 3^x - 1 preliminary check: if x = 1 4+3 = 7 < 9 if x = 2 16 + 9 = 25 < 81 .. if x = 6 4^6 + 3^6 = 4825 < 9^6 for x ≥ 1, the gap between LS and RS is increasing, and RS > LS let's ...

*October 23, 2016*

**Maths**

written as a recursive : t(1) = 6 t(n) = t(n-1) + k+1, where k >1 as a function of n, double the terms: 12, 20, 30, 42 ... 12 = 3*4 20 = 4*5 30 = 5*6 42 = 6*7 looks like t(n) = (n+2)(n+3)/2 <--- remember we doubled

*October 23, 2016*

**Mathematics**

the equation must look like: y = a(x-2)^2 - 8 and it must pass through (0,0) 0 = a(-2)^2 - 8 8 = 4a a = 2 equation: y = 2(x-2)^2 - 8

*October 23, 2016*

**Math**

let's consider midnight as time zero 10:43 - 8:17 = 2:26 So it must have left 2 hours and 26 minutes before midnight, or the bus left town A at 9:34 pm or: we could use international time format let's add 24 hours to 8:17 to get 32:17 and 32:17 - 10:43 = 21:34 which is...

*October 23, 2016*

**Maths**

In a rectangle, the two diagonals right-bisect each other. Since they are equal, and we are told the angle between them is 45°, our rectangle must be a square. let the side of the square be x x^2 + x^2 = 6^2 2x^2 = 36 x^2 = 18 x = √18 = 3√2 or appr 4.26 cm The ...

*October 23, 2016*

**math**

360 = 2*2*2*3*3*5 = (2^3)(3^2)(5)

*October 23, 2016*

**math**

how many 3/8 's do you see? 3/8 x 3/8 x 3/8 = (3/8)^3

*October 23, 2016*

**Algebra**

Just concentrate on copper only. let the amount of the 70:30 alloy used be x g then the amount of the 40:60 alloy used is 300 - x .7x + .4(300-x) = .6(300) .7x + 120 - .4x = 180 .3x = 60 x = 200 so 200 g of the 70:30 alloy and 100 g of the 40:60 alloy checking for the zinc: .3...

*October 22, 2016*

**math**

x and y are defined in the question, so the cost equation would be cost = 13x + 18y so for b) you know cost = 168, x = 6 168 = 13(6) + 18y 168 = 78 + 18y 90 = 18y y = 90/18 = 5 He bought 6 t-shirts and 5 pairs of jeans

*October 22, 2016*

**PLEASE HELP Math**

amount of 1st part: i = .08/12 = .006666.. n = 96 paym = 50 amount = 50( 1.0066..^96 - 1)/.00666.. = $6693.43 amount of 2nd part: i = .10 n = 4 paym = 2000 amount = 2000(1.1^4 - 1)/.1 = $9282.00 total amount = $6693.43 + $9282.00 = $15,975.43 Looks like Colin is not yet ready ...

*October 22, 2016*

**Math**

i = .15/12 = .0125 n = 24 payment = 23 PV = 23( 1 - 1.0125^-24)/.0125 = 474.36

*October 22, 2016*

**integrals**

The word "power rule" is usually associated with derivatives, but your subject title is "integrals" so what do you want done with it 1/((x^2+4))^2 = (x^2 + 4)^-2 dy/dx = -2(x^2 + 4)^-3 (2x) = -4x/(x^2 + 4)^3 if you want to integrate, it will be a bit harder.

*October 22, 2016*

**math**

Of the two choices, only a) and b) have a slope of -6 (-12,5) does not satisfy a) but it does satisfy b) so b)

*October 22, 2016*

**Math**

I will assume that the three smaller parts are equal rectangles. Let the width of one of the smaller rectangles is x and its length is y Make a sketch and you should see that our original field is 3x by y and perimeter is 6x + 4y so 6x + 4y = 2400 3x + 2y = 1200 y = (1200 - 3x...

*October 22, 2016*

**Math**

cost(d) = 35d + 14.95d + 19(3.40) = 49.95 d + 64.60 where d is the number of days So for 9 days, replace d with 9 and evaluate.

*October 22, 2016*

**Business Mathematics**

Just use your formulas "8th term is 18" ---> a + 7d = 18 "11th term is 24 ---> a + 10d = 24 subtract them: 3d = 6 d = 2 in a+7d = 18 ---> a + 14 = 18 , a = 4 now use your sum(n) formula your a = 4 d = 2 n = 13

*October 22, 2016*

**Math, Functions**

I disagree with what Christos did it said solve g(t) = 0 , not find g(0) First of all I am sure you meant: g(t) = 1/(t-2) - 1 so if g(t) = 0, 1/(t-2) - 1 = 0 1/(t-2) = 1 t - 2 = 1 t = 2

*October 22, 2016*

**math**

let the work to be done be 1 unit rate of first crew = 1/8 job done by first crew in 2 hours = 2(1/8) = 1/4 job left to be done = 1 - 1/4 = 3/4 rate of second crew = 1/10 time needed for 2nd crew to finish = (3/4) / (1/10) = 30/4 hrs or 7.5 hrs

*October 22, 2016*

**Maths**

original rectangle: area = 7(4) cm^2 = 28 cm^2 new rectangle: area = (14)(8) cm^2 = 112 cm^2 ratio of new to old = 112 : 28 = 4 : 1 The ratio of the areas of similar figures is proportional to the square of their corresponding sides, that is 2^2 : 1^2 = 4 : 1

*October 22, 2016*

**math**

How many seconds are there in 1 hour? multiply that by 24

*October 22, 2016*

**Precalc**

let each of the equal sides of the triangle be x let the radius of the circle be r area = (1/2)(x)(x) + πr^2 = x^2/2 + πr^2 we know that if the hypotenuse of the triangle is is h x^2 + x^2 = h^2 2x^2 = h^2 h = x√2 then 2x + √2 x + 2πr = 100 r = (100...

*October 21, 2016*

**Math**

correct

*October 21, 2016*

**math**

1/3 * -1 1/5 the * symbol is used in this format to stand for multiplication so if you mean (1/3)(-6/5) , then = - 6/15 = -2/5 or -0.4

*October 21, 2016*

**Maths**

6^2 + 2^2 + 3^2 = 49 so the direction cosines are (6/7 , 2/7, 3/7) notice that (6/7)^2 + (2/7)^2 + (3/7)^2 = 1

*October 21, 2016*

**Math**

I agree

*October 21, 2016*

**Math**

Treat the question as if you had two ordered pairs (3,800) and (5,720) slope = (720-800)/(5-3) = - 40 using(3,800) y - 800 = -40(x-3) y = -40x + 920 b) so after 1 year, x = 12 y = -40(12) + 920 = 440 state your conclusion using the proper units

*October 21, 2016*

**Math**

Rent it Cheap = 2900 + 50k Thrift car = 3700+48k solve 2900+50k = 3700+48k and use the result to state your conclusion

*October 20, 2016*

**Algebra**

2𝑦 + 5 = 1/2(4𝑦 + 8) multiply both sides by 2 4y + 10 = 4y + 8 10 = 8, ahhh, I see your problem, the y's dropped out ok, if your variables drop out, and you end up with a false statement, such as our 10=8, then the equation has no solution. If we end up ...

*October 20, 2016*

**Math**

"2n up3" ?? did you mean 2n^3 ? or perhaps (2n)^3 ? clarify please.

*October 20, 2016*

**Math**

let the middle number be x then x/5 = 245/x x^2 = 1225 x = ± 35

*October 20, 2016*

**Math**

940 = 20 x 47 ---> 47 is prime 420 = 20 x 21 The GCF = 20

*October 20, 2016*

**maths**

c) ii) you asked how many study French, but your first data information says that 9 study French Either you meant 9 to be "French only" , or else the question is bogus. Confirm.

*October 20, 2016*

**Algebra**

area of the 4 windows = 4(30/12)(48/12) = 40 ft^2 area of floor = 10(40) = 400 ft^2 (where does the ridiculous height of 50 ft come in ?) ratio of window area : floor area = 40:400 = 1:10

*October 20, 2016*

**Math**

1st derivative: -sinx 2nd derivative: -cosx 3rd derivative: sinx 4th derivative: cosx 5th derivative: -sinx .. 14th derivative: etc. notice we are in a cyclical loop of 4 results, notice 999 leaves a remainder of 3 when divided by 4, so the result is the same as the 3rd ...

*October 20, 2016*

**Math help please!**

done, look at Dan's problem below. Are you switching names?

*October 18, 2016*

**Math Please help**

let the number of units be x return = 9x cost = .4(9x) + 50000 at "break-even" point, they are equal 9x = 3.6x + 50000 5.4x = 50000 x = 9259 carry on

*October 18, 2016*

**Algebra**

Neither one has an average elevation of -2 Average elevation of Long Beach = (360 + (-7) )/2 = 176.5 units You do the other one in the same way to show the question is bogus

*October 18, 2016*

**Science, Math**

Your choices make no sense to me

*October 18, 2016*

**Science Earth**

If 10 million years ----> 1 cm 4.6 billion/(10million) = 4.6 x 10^9/(10 x 10^6) = 460 You will need 460 cm or 4.6 metres

*October 18, 2016*

**Maths**

346° + 30° = 376° = 360° + 16° = 1 rotation + 16°<----- same as a direction of 16°

*October 18, 2016*

**Geometric progression**

apparently three numbers are in a GP then the 3 numbers are: a, ar, and ar^2 "the continued product of three numbes in g.p. is 216" I am guessing you mean: a(ar)(ar^2) = 216 a^3 r^3 = 216 ar = 6 a = 6/r "the sum of their products in pair is 156" a(ar) + a(...

*October 18, 2016*

**Geometric progression**

Let the original numbers be a, a+d, and a+2d 3a + 3d = 15 or a+d = 5 ----> d = 5-a after the addition, the three numbers are: a+1, a+d+4, and a+2d+19 they are now in GP, that is .... (a+d+4)/(a+1) = (a+2d+19)/(a+d+4) (a + 5-a + 4)/(a+1) = (a + 10-2a + 19)/(a + 5-a + 4) 9/(a...

*October 18, 2016*

**Algebra2**

following up on John's observation, let y = k/x for (5,2) 2 = k/5 k = 10 y = 10/x check for (10,1) is 1 = 10/10, yes check for the last one: (20, 1/2) is 1/2 = 10/20 , yes

*October 17, 2016*

**Math**

If 3/8 of the 240 students are boys, then 5/8 will be girls or 15 will be girls. 3/5 of the girls have short, so I will assume that 2/5 will have long hair, assuming none of the girls are bald (2/5)(15) = 6 6 of them have long hair

*October 17, 2016*

**Math**

because I can write is a fraction .57 = 57/100

*October 17, 2016*