Friday

July 25, 2014

July 25, 2014

Total # Posts: 26,867

**Algebra where did I go wrong**

Mark, the correct answer is 10 Please trust Damon.

**Algebra**

prob (2 yellow) = (6/15)(6/15) = 36/225 = 4/25 Since you are returning the first marble picked, the second probability is the same as the first one.

**Precalculus**

I followed your description ok. so we get: -8 + 2x + 15 = 9 2x = 2 x = 1 10 + 3x + 25 = 38 3x = 3 x = 1 , confirming our first answer 4 - 3x + 5 = y 4-3+5=y y = 6 So x = 1 , y = 6

**algebra**

let d be the number of DVD's rented 2d + 6 = 48 2d = 42 d = 21 If the customer borrows less than 21 DVD's the first plan is better If the customer borrows 21 DVD's s, the cost is the same If the customer borrows more than 21, the flat rate of $48 is best.

**math (last question #5) @Damon**

if c is 8y^2 - 10y + 3 , then yes.

**Math 8th gr.**

27 - (-9) (-2) ÷ 3 * (-4) - 0 - 33 - (-39) just follow the rule of operations ... 27 + 24 - 0 - 33 + 39 = 57

**MATH**

makes no sense. We don't know the distribution of boys to girls in the 12 middle schoolers.

**maths**

yes, what about it? The statement is true.

**math test**

Pacific = x Caribbean = x+32 Medi = 4x - 38 x+x+32+4x-38 = 828 you solve it, it is easy

**Calculus**

so one side is not needed. let the two width be x m let the one length be y m 2x + y = 1000 y = 1000 - 2x area = xy = x(1000-2x) =1000x - 2x^2 d(area)/dx = 1000 - 4x = 0 for a max of area 4x = 1000 x = 250 y = 1000-500 = 500 max area = xy = 250(500) = 125000 m^2

**Calculus**

dd/dt = 1200 - 72000t = 0 for a max 72000t = 1200 t = 1/60 d = 1200(1/60) - 36000(1/3600) = 10 m

**Algerbra 2**

ummhhh, value in 6 years = 118000(1.09)^6

**Algerbra 2**

value in 6 years = 118000(1.09)^6 = ....

**Algebra**

total = 2x+1 + 3x + x+2 = 6x + 3 prob red = (2x+1)/(6x+3) = (2x+1)/(3(2x+1) ) = 1/3

**math**

FF -- x DD -- y RR -- z x+y+z = 41.70 , #1 2x + z = 37.95 , #2 x+y = 26.75 , #3 #1 - #3" z = 14.95 sub into #2 2x + 14.95 = 37.95 2x = 23.00 x = 11.50 sub into #3 11.50 + y = 26.75 y = 15.25 FF costs 11.50 DD costs 15.25 RR costs 14.92

**Math**

your slope of -2/5 or -.4 for line AB is correct The slope of a line can be any real number, both positive and negative If the slope is positive the line leans to the right If the slope is negative the line leans to the left if the slope is zero, the line is horizontal.

**Precalculus**

Since you are given the slope and the y-intercept, the problem becomes a matter of just subbing in the values y = (5/8)x + 4

**Algebra**

19 P 2 = 19!/(19-2)! = 19(18)(17!)/(17! = 19(18) = 342 If by "if there is no r" you mean "if the value of r = 0" then 4P0 = 4!/(4-0)! = 1

**Algebra**

Damon, I think you forgot to divide by 7 before taking the square root. SD = √(80/7) = 3.3806 The amazing Wolfram supports this http://www.wolframalpha.com/input/?i=standard+deviation+4%2C+8%2C+5%2C+12%2C+3%2C+9%2C+5%2C+2

**geometry**

So you need the length of the hypotenuse sin 13° = 186/x x = 186/sin13° = 826.8 ft

**algebra**

width --- x length -- 2x+4 x(2x + 4) = 400 2x^2 + 4x = 400 x^2 + 2x = 200 x^2 + 2x + 1 = 200 + 1 (x+1)^2 = 201 x+1 = ± √201 x = -1± √201 x = appr 13.18 cm or a negative, which we will reject The width is appr 13.2 and the length is appr 30.4

**math homework help**

PV = 125000(1.03)^-5 = $107,826.10

**Math: Linear Equation**

A linear equation of your type will produce a straight line when graphed. So all you need are 2 distinct points. Using the x and y intercepts are a quick and easy way to do this, after all the intercepts are just plain ol' points. Here is an easy way to do this: let x = 0 ...

**math**

distance = 7(55) miles = 385 miles number of gallons of gas = 385/30 = appr 12.8 or 13 gallons

**no**

3 undecillion http://www.thealmightyguru.com/Pointless/BigNumbers.html in scientific notation: 3.0 x 10^36 A rather large number, considering that the total number of grains of sands are estimated to be only about 7.5 x 10^18 and Carl Sagan claimed that there are more stars in...

**Math**

I even tried this to see the median answer http://www.wolframalpha.com/input/?i=sort+19%2C+19%2C+14%2C+14%2C+16%2C+19%2C+19%2C+16%2C+16%2C+15%2C+17%2C+16%2C+17%2C+16%2C+15%2C+14%2C+15%2C+15%2C+17%2C+14%2C+16%2C+15

**Math**

Wow, I didn't know that Wolfram does even this stuff This wonderful webpage amazes me more all the time. http://www.wolframalpha.com/input/?i=mean+19%2C+19%2C+14%2C+14%2C+16%2C+19%2C+19%2C+16%2C+16%2C+15%2C+17%2C+16%2C+17%2C+16%2C+15%2C+14%2C+15%2C+15%2C+17%2C+14%2C+16%2C+...

**statistics**

prog(right) = 1/5 prob(wrong) = 4/5 prob of your stated event is, getting none right --> C(12,0)(1/5)^0 (4/5)^12 = .0687 getting one right --> C(12,1) (1/5) (4/5)^11 = .20616 getting two right --> C12,2) (1/5)^2 (4/5)^10 = .2835 getting three right --> C(12,3) (1/5...

**Algebra**

z-score = (given value - mean)/sd -1.7 = (13 - 18.1)/sd -1.7sd = -5.1 sd = -5.1/-1.7 = 3

**Need help with pre cal hw**

1. I sketched a triangle, and noticed I could use the cosine law: R^2 = 8^2 + 6^2 - 2(8)(6)cos 50° = 38.2923... R = appr 6.189 km or use vectors first vector = (8cos30 , 8 sin 30) = (6.9282 , 4) 2nd vector = (6cos160, 6sin 160) = (-5.63815.. , 2.05212) sum = ( 1.29004.... ...

**math**

a reflection across the y-axis causes the x value to become opposite, while the y stays the same using your wording: (x,y) ----> (-x + 1, y - 2) A(1 , -3) ----> A' (0, -5) B(4 , -5) ----> B' (-3 , -7) C(3 , -1) ----> C' (-2 , -3) You should really have ...

** RE-TYPE**

Oh no, log6 is not a number, it is an operator. You can't factor out log6 (that would be doing something like √8 - √3 = (√)(8-3) ) You have to use your rules of logs. log6(x+3) - log6(x-5) = 2 log6 ( (x+3)/(x-5) ) = 2 which by definition is (x+3)/(x-5) = ...

**Calculus**

Oh no, 6 is not a number, it is an operator. You can't factor out 6 (that would be doing something like √8 - √3 = (√)(8-3) ) You have to use your rules of logs. 6(x+3) - 6(x-5) = 2 6 ( (x+3)/(x-5) ) = 2 which by definition is (x+3)/(x-5) = 6^2 = 36 36x - ...

**Calculus**

log5 16807^5 - log57^3 = log5A log5 (16807^5/7^3) = log5A A = 16807^5 / 7^3 = 49(16807)^4 = appr 3.91 x 10^18

**maths**

I strongly recommend that you mind your p's and q's

**Calculus**

The way you typed R(t), we have to read it as R(t) = 9/2.718 ( t(t-3)^3) then R' (t) = (9/2.718) [ t (3)(t-3)^2 + (t-3)^3 ] = (500/151)(t-3)^2 ( 3t + t-3) = (500/151)(4t - 3)(t-3)^2 How did the base of (t-3) suddenly turn into (t-4) ?

**algebra**

balance on home = .08(118,000) = $94,400 i = .095/12 = .00791666... n = 30(12) = 360 paym( 1 - 1.00791666..^-360)/.00791666.. = 94400 payment = $793.77

**algebra**

a) since 0% interest, the monthly payment would simply be 42500/60 = $708.33 b) I believe in the US , add-on-interest is done this way: amount to be financed = 42500-5100 = 37400 interest = 37400(.025)(5) = 4675.00 total of loan = 37400 + 4675 = 42075.00 monthly payment = 4207...

**math**

Unfortunately , the expression and measurement of time is not metric, so we have to make some changes. (similar to the US method of working in miles, yards, feet and inches) (14 hrs, 3 min)/3 = (13 hrs, 63 min)/3 = 4 1/3 hrs, 21 minutes = 4 hrs, 20 min , 20 min = 4 hrs and 41 ...

**math**

Does it fit the description I gave you? How about some thinking on your part after all your posts ?

**math**

in a reflection in the x-axis, all the x values stay the same, but the new y's become opposites of the old ones now, which matches that description.

**math**

prob(under 25) = .55 prob(over 25) = .45 prob (exactly 4 of 6 are under 25) = C(6,4) (.55)^4 (.45)^2 = .27795

**Math**

(-8x)(3x^2) = -24x^3

**math**

10 ---> 1 , looks like it went left 9 3 ---> 6 , looks like it went up 3

**math**

just evaluate y for the given x's and plot the points e.g , when x = -2 y = (1/3)(2) - 2 = 2/3 - 2 = -4/3 ------> so you have the point (-2, - 4/3

**math**

Actually I just noticed your equation is not quite clear. is the exponent 3 ? then you would have written it as y = 2x^3 or did you forget to type the exponent ? It would be highly unusual for a text to put the + sign in front of the exponent like you typed it.

**math**

evaluate the y for the given x's, then plot the points. Join them with a smooth curve. You will get a parabola

**Math**

Assuming your ã is √ #3 , the -11√8 becomes -22√2 the rest are correct

**alegbra/stressed**

in each case you divide the rate by the annual compounding frequence, and multiply the years by that annual compouding frequency e.g. if compounded quarterly, the annual compounding frequencey is 4 I will do that one, you try the others. 6.9 %> compounded quarterly i = .069...

**Math**

I think we should use compound interest here. i = .09/12 = .0075 let the payment be p p( 1 - 1.0075^-36)/.0075 = 100000 p = $3179.97

**Chemistry, not Math**

label your problem using the right subject

**math**

for the 1st pair, since you know what y is , just plug that value into the first equation and solve for x #2: 3x - 14y = 0 x - 4y + 1 = 0 3x - 14y = 0 multiply the 2nd by 3 3x - 12y = -3 subtract them -2y = 3 y = -3/2 sub into x - 4y = -1 x - 4(-3/2) = -1 x + 6 = -1 x = -7 x =...

**math**

4(2x-9)-4x= 4-6x 8x - 36 - 4x = 4 - 6x 10x = 40 x = 4 16y plus 4 =-10 16y + 4 = -10 Does your keyboard not have a + sign? 16y = -14 y = -14/16 = -7/8

**Math**

it is called a subscript it is not an actual mathematical operator, but instead is an indicator. e.g. you often see it to label two points (x1 , y1) and (x2 , y2) to state that you have two points of the form (x,y) but the x's and y's are different e.g. if you have two...

**maths**

What does "works up to" mean in mathematics ????

**Math**

942!/(15n) = 942x941x940x939x938!/(15n) = 942(941)(188)(313)(938!)/n I divided by 5 and by 3 leaving the division by n

**Math**

multiply top and bottom by √6 + √3 (2 √ 6 + √ 3)/ ( √ 6- √ 3) * (√6 + √3)/(√6 + √3) = ( 12 + 3√18 + 3)/(6-3) = (15 + 9√3)/3 = 5 + 3√2

**Calc Help Please Again Last one!**

I will split it up for you ... (6x-58)/( (x+9)(x-7) ) let A/(x+9) + B/(x-7) = (6x-58)/( (x+9)(x-7) ) A(x-7) + B(x+9) = 6x - 58 let x = 7 0 + 16B = -16 B = -1 let x = -9 -16A + 0 = -112 A = -7 so .... (6x-58)/( (x+9)(x-7) ) = -7/(x+9) - 1/(x-7) now it integrates easily using ln...

**Calc Help Please Again!**

can't tell if your equation is y = e^(x+4) or y = e^x + 4 , why is there a 1 in front of the x ?

**Calc Help Please**

I got (1/4) (ln(x-2) - ln(x+2) ) + c how did your x-2 from the original denominator turn into 2-x) I used partial fractions

**Geometry**

make a sketch to see that height/36 = tan 25° height = 36tan25 = appr 16.8 ft

**Algebra**

yes

**alegbra**

my equation, (very close to yours) 225500 = PV e^(8.4246575(.0855)) 225500 = PV e^(.720308219) , now press 2nd ln 225500 = PV (2.055066524) PV = 109,728.81 I let the calculator carry all the decimal places and only rounded off my final answer to the nearest cent. You were off ...

**math**

distance = √( (-3-8)^2 + (-10+10)^2) = √(121 +0) = √121 = 11 We can see this without any calculation. Since the x values are the same for both points, the line is a vertical one. So all we have to do is take the difference between -3 and 8 , which is 11

**math**

number of $5 tickets --- x number of $10 tickets --- y number of $15 tickets ---- 180-x-y x + (180-x-y) = 2y x + 180 - x - y = 2y 180=3y y = 60 income equation: 5x + 10y + 15(180-x-y) = 1900 5x + 600 + 15(120-x) = 1900 5x - 15x + 600 + 1800 = 1900 -10x = -500 x = 50 x=50 y=60 ...

**math(compound interest )**

What you wanted as an equation is ... [ x( 1 + .1/360)^20 - 600 ](1+.1/360)^108 = 8900 x(1+.1/360)^20(1+.1/360)^108 - 600(1+.1/360)^108 = 8900 x((1.00557024)((1.03045024) - 618.2701442 = 8900 x(1.036190095 = 9518.270144 x = 9185.83

**math trigonometry**

I don't understand your question. Are we looking at two different equations ? Are we solving 10 sec Ø + 13sinØ = 0 and 5tan Ø - 12 = 0 ???? or .... ? is (0,90°) the domain?

**Algebra 1**

first equation: -2x - 2y = 4 ----> x+y = -2 2nd equation: 2y = -2x - 4 2x + 2y = -4 x + y = -2 looks like they are the same line, so you have one line any ordered pair that works in one of them, will work in the other. There will be an infinite number of solutions.

**Math-- Ms. Sue??**

#1 , wrong. If you plot your points you will see that it is (8,5) notice that now two pairs of points have the same x , making the lines vertical, and 2 pairs of points have the same y, making the horizontal. #2, ok #3, ok #4, your answer: (5,-4) and (-2,1) -- slope = (1-(-4))...

**Math**

prob(brown, then violet) = (8/16)(1/16) = 1/32

**Math - Int Trig**

y = √x shift up 4 units -----> y = √x + 4 reflect about the y-axis ---> y = √-x + 4 , for x ≤ 0 shift right 2 units -----> y = √(-(x-2)) + 4 , x≤2 again, Wolfram verifies this http://www.wolframalpha.com/input/?i=y+%3D+√%28-%2...

**Math - Int Trig**

start: y = |x| shifted right : y = |x-3) stretched by factor of 3 : y = 3|x-3| vertically down 2: y = 3|x-3| - 2 reflected about x-axis y = -3|x-3| + 2 behold the wonders of Wolfram http://www.wolframalpha.com/input/?i=y+%3D+%7Cx%7C+%2C+y+%3D+%7Cx-3%7C+%2C+y+%3D+3%7Cx-3%7C+%2C...

**math**

multiply each of the prob. answers I just gave you by 100

**math**

Four possible outcomes: HH HT TH TT prob(HH) = 1/4 prob(TT) = 1/4 prob (TH or HT) = 2/4 = 1/2 notice the 3 answers add up to 1, since one of those possibilities must happen

**Geometry**

(-3,-1) ---- dilation factor of 2 ----> (-6, -2) show it by plotting the two points how does the distance to the origin change ?

**Algebra 1**

looks like f(3) = 2 then g( f(3) ) = g(2) = -3

**Trig 3**

sloppy way of writing the trig expressions ( when you write tan2, you are asking for the tan(2 radians. What you meant was something like tan^2 Ø It has to be the sine of something, the cosine of something, or the tangent of something. anyway ..... (1 - cos^2 Ø)/...

**Geometry**

Any regular n-gon can be changed to n isosceles congruent triangles by drawing all radii to the vertices of the polygon. the area of a triangle = (1/2)(base)(height) the area of one of these = (1/2)(side)(apothem) where the apothem is the distance from the centre of the polygo...

**math(compund interest )**

Major Hint: Did you notice that from 16 April to 16 Oct is 6 months? So your time can be very easily expressed in half-years, and quarter-years. From all the knowledge you have gained by having received many answers for similar questions to the above, you should now be able to...

**mathematics for management**

NO you used the concept of continuous compounding but it said it was compounded monthly Even with the above in consideration your expression of 8888(e^0.06(0.25)) makes absolutely no sense. i = .06/12 = .005 n = 3(12) = 36 months PV = 8888(1.005)^-36 = $7427.21 For a single in...

**math**

How do you expect us to know what table you are working from. With today's excellent scientific calculators, the use of "tables" that were found in the back of most textbooks in the past is no longer common practise. Your question is simply PV = 100000(1.05)^-50 ...

**math**

what is 20000(1.06)^15 ?

**math(urgent)**

Just use the formula. Amount = payment( (1+i)^n -1)/i Amount = 1000(1.08)^3 -1)/.08 = 3246.40

**Trig**

3x^2 + 4y^2 = 12 divide by 12 x^2/4 + y^2/3 = 1 we know sin^2 t + cos^2 t = 1 so sin^2 t = x^2/4 = (x/2)^2 ---> sin t x/s ----> x = 2sin t and cos^2 t = y^2/3 = (y/√3)^2 cos t = y/√3 ----> y = √3cos t x = 2sint y = √4cost confirmation: http://w...

**Calculus**

dy/dx = 2tan (x^4) * sec^2 (x^4) * 4x^3

**ALGEBRA**

using the ratios, let the width be 8x and the length be 15x led d be the diagonal d^2 = (8x)^2 + (15x)^2 = 64x^2 + 225x^2 = 289x^2 d = 17x or x = d/17 width = 8x = 8d/17 length = 15x = 15d/17

**geometry**

volume of similar solids is proportional to the cube of their corresponding sides so ratio of volume = 3^3 :^3 = 27 : 125

**Math**

so you want 9(2)(t/9) = 1000000 2^(t/9) = 111,111.111.. t/9 log2 = log111111.11 t/9 = log111111.11../log 2 = 16.7616.. t = 150.8548 years so 1909 + 150.8548 yrs = appr 2060 just what Ms Sue got by continuing her chart.

**math**

1.75 years = 21 months monthly rate = .18/12 = .015 PV = 900(1.015)^-21 = $658.35

**math**

100% of something = the whole thing or 1 50% of something = .5 or 1/2 of the whole thing = .5 145% of something = 1.45 yes, C is the right choice.

**math (urgent )**

my answer confirmed by Wolfram http://www.wolframalpha.com/input/?i=13.875-0.1875%2856.375%29%2F8-2+%281%2F8%2B27.125%2F300.875%29+

**math (urgent )**

This is what you typed: 13.875-0.1875(56.375)/8-2 (1/8+27.125/300.875 I added a bracket at the end, or else they are mismatched. Followed the order of operation, and got 12.1234035... The way you wrote it, there is now way to get 1.1908 check how you placed your brackets.

**Geometry Help & Proofs**

based on : ratio of volumes is proportional to the cube of their corresponding sides. so ratio of volumes: A : B = 1 : 5 A : C = 1^3 : 2^3 = 1 : 8 B : D = 1^3 : 3^3 = 1 : 27 A/B = 1/5 B = 5A A/C = 1/8 C = 8A B/D = 1/27 D = 27B ratio of volume of C :D = 8A : 27B = (8/27)(A/B) =...

**Math**

9/9 = 1 = 12/12 2/3 = 8/12 5/6 = 10/12 4/12 = 4/12 0/2 = 0 , obviously the smallest now can you tell ?

**Algebra**

(x - y) (3x + xy - 4y) + xy^2 - x^2y = (x-y)(3x + xy - 4y) - xy(x - y) = (x-y)(3x + xy - 4y - xy) = (x-y)(3x - 4y)

**Math**

The total of the first 16 students' marks was 16x66 or 1056 the total of the new students' marks was 6x74 or 444 so the total of the 22 students was 1500 giving an average of 1500/22 or appr 68.2

**finance**

WoW! I recognize the formula Future Value = Present Value (1 + i/n)^(cn) where n is the frequency of compounding per year and c is the number of years from your (1.089/12)12*5 I gather that the interest rate was 8.9 % per annum compounded monthly , for a time of 5 years and yo...

**Algebra 1 Answer Evaluation**

anything squared cannot be negative in the real number set, so your first one has no real number solution 2. correct

**math**

distance (d) ∝ time (t) d = kt case 1: when t = 2 , d = 90 90 = k(2) k = 45 so d = 45t , the constant of proportionality is 45 the unit rate is 45 mph check on the others t = 3 --> d = 45(3) = 135 ✔ t = 5 --> d = 45(5) = 225 ✔ t = 6 --> d = 45(6) =...

**Algebra 1 (Reiny)**

x^2 + 3x - 18 = 0 (x+6)(x-3) = 0 x = -6 or x = 3

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