Sunday

April 20, 2014

April 20, 2014

Total # Posts: 26,042

**Algebra 2**

the way you typed it, multiply each term by 2 x^2 + 4x + 6 = 0 complete the square ... x^2 + 4x + 4 = -6+4 (x+2)^2 = -2 x+2 = ± √-2 x = -2 ± i√2

**For Sam - math**

Even if tossing around a few numbers often yields the "correct answer", the statements must be mathematically correct and logically sound look at your statement: 3/5 = 2+4 , now that is news to me, I always thought 2+4 is 6 and not 3/5 Do you see what I mean ? .........

**math**

tan E = y/x = (4/5) / (3/5) = 4/3

**Algebra**

in standard form we usually lead with the x term with a positive coefficient, so I wanted a +x as my first term, it was -x . to change a standard form to slope- yintercept form usually takes 2 steps: 1. move all terms except the y term to the right e.g. 4x - 5y = 8 ---≥ ...

**Algebra**

your slope is correct as +1 your equation of y+1 = 1(x+2) is also correct then y+1 = x+2 y = x+1 ---> slope-yintercept form y-x = 1 x - y = -1 ----> standard form ( I multiplied each term by -1)

**math**

first round: x --> 3x --- >3x-2 2nd round: 3x-2 ---> 9x-6 ---> 9x-8 3rd round: 9x-8 ---> 27x - 24 ---> 27x - 26 27x - 26 = 271 27x = 297 x = 11

**math question grade 8!!**

Wow, those rooms are pretty small even for a doll-house.

**Math - Calculus I**

Draw a side view of the situation (The cone will look like an isosceles triangle with a rectangle (the cylinder) sitting on its base and touching the sides) let the radius of the cylinder be r and let the height of the cylinder be h Look at the small right-angled triangle at t...

**Math**

A new number is obtained by adding the 3 previous ones.

**Math**

let the 6 consecutive multiples of 6 are 6x , 6x+6 , 6x+12, 6x+18, 6x+24 and 6x+30 their sum is 36x + 90 the LCM of 13 and 18 is 234 36x + 90 = 234 36x = 144 x = 4 So the number are : 24, 30, 36, 42, 48, and 54

**Algebra 1**

Let the time traveled by each one be t hrs distance gone by first = 125t miles distance gone by 2nd = 120t miles 125t + 120t = 735 245t = 735 t = 3 After 3 hrs, they will be 735 miles apart

**Algebra**

You must mean y = x^2 - 2x - 15 , note how we show exponents. =(x-5)(x+3) so the zeros are -3 and 5

**Math**

1. (4/5)(5/7) = 4/7 2. -1 1/6 ÷ 2/9 = (-7/6)(9/2) = -63/12 = -21/4 or -5 1/4 3. (-32/5) ÷ (-16/7) = (-32/5)(-7/16) = 14/5 or 2 4/5 4. You do this one the same way I showed you

**Statistics**

true

**Statistics**

true, but your answer should be reduced to 1/6

**TO REINY**

You are very welcome

**Advanced Functions/Precalculus**

2. 7sin^2x - 4sin2x/cosx = -1 7sin^2 x - 4(2sinxcosx)/cosx = -1 7sin^2x - 8sinx + 1 = 0 (7sinx - 1)(sinx - 1) = 0 sinx = 1/7 or sinx = 1 if sinx = 1 x = 90° or π/2 if sinx = 1/7, then x = aprr 8.2° or 171.8° 3. cos 2Ø = cos^2 Ø - sin^2 Ø g...

**Advanced Functions/Precalculus**

will you take a look at the fun that even Wolfram had in solving the equation the way you typed it ??? http://www.wolframalpha.com/input/?i=solve+sin2x%2B1%3D-2sinx I have a feeling that you meant: sin^2 x + 1 = -2sinx then sin^2 x + 2sinx + 1 = 0 (sinx + 1)^2 = 0 sinx +1 = 0 ...

**math**

slope = (7-2)/(3-(-5)) = 5/8 y-7 = (5/8)(x-3) 8y-56 = 5x - 15 -5x + 8y = 41 5x - 8y = -41 in standard form 5x - 8y + 41 = 0 in general form y = (5/8)x + 41/8 in slope - yintercept form

**math**

We can't do diagrams in this forum Possible paths to get from lodge to entrance via dock AC AD BC BD I will do one length , you do the others; BC = 2/3 mile + 1/4 mile = (8+3)/12 = 11/12 miles

**Algebra 1**

1. Area of a square = (x^2)^2 = x^4 (each side is x^2, area of a square = side^2 so (x^2)(x^2) = x^4 ) 2. when x = 5 area = 5^4 = 625 3. when x = 10 area = 10^4 = 10000

**Math**

number of short-sleeved shirts --- x number of long-sleeved shirts --- 63-x 15x +22(63-x) = 1134 15x + 1386 - 22x = 1134 -7x = -252 x = 36 so 36 short-sleeved and 27 longsleeved shirts

**Calculus**

the shape you will get is half a torus. A torus is a donut or bagel shaped solid. We have cut ours in half (to make a tasty cream-cheese bagel) the y-intercepts: 0 = y(9-y) so y = 0 or y = 9 , You had that so we need the radius of the outer and the inner rings: y^2 - 9y = -x y...

**Math (PreCalculus)**

I get log(1584893) = 6.199999 or 6.2 not 6.268

**Can anyone help me with this?**

Disagree with 1. My Canada is the 2nd largest country in terms of area, but has only 35 Million, about 1/10 of yours. I would pick C

**help please math**

i = .06/24 =.0025 n = 5(24) = 120 Let the payment be P P( 1 - 1.0025^-120)/.0025 = 18000 I get P = $173.81

**math**

payment -- P P( 1 - 1.17^-20)/.17 = 250000 I get P = $44,422.59

**math**

Where are you getting these magical 18% and 17% ?? Amount = 10( 1.015^540 - 1)/.015 = $2,067,433.43

**Advanced Functions/Precalculus**

11π/12 is π/12 short of 2π so tan 11π/12 = -tan π/12 I know tan 2π/12 = tan π/6 = 1/√3 tan 2π/12 = 2tanπ/12/(1 - tan^2 π/12) let x = tan π/12 for easier typing so 1/√3 = 2x/(1 - x^2) 2√3x = 1 - x^2 x^2 + ...

**MATH.**

C(9,6) = 9!/(6!3!) = 362880/(720 x 6) = 84 you should have a C(n, r) key on you r calculator sometimes shown as nCr on mine it is found under the "5" key so enter 9 nCr 6 = to get 84

**Geometry**

measured along the diagonals, so diagonal is twice as big

**Geometry**

I will do the 1st one you do the 2nd method 1. check to see if it is right -angled, then it would be real easy is 3.5^ + 4.8^2 = 6.1^2 ? , NO --- so forget that method method 2: find the angle opposite the smallest side using the cosine law 3.5^2 = 4.8^2 + 6.1^2 - 2(4.8)(6.1)c...

**math**

You must have a typo If you want me to use the stated property, then you must have meant 9^(-x+15) = 27^x if as assumed, then (3^2)^(-x+15) = (3^3)^x 3^(-2x + 30) = 3^3x -2x + 30 = 3x , using your stated property -5x = -30 x = 6

**math**

You will also have to insert brackets to clarify the order of operation here e.g. I will do the 2nd one assuming you meant: 7√(2x) + 2√(72x^3( - √(162x^5) = 7√(2x) + 2√(2x) √(36x^2) - √(2x) √(81x^4) = 7√(2x) - 12x√(2x...

**Math**

area of circle = π(7^2) = 49π prob of landing in circle = 49π/420 = 7π/60 = appr .3665 ignoring any leaves that fall partially either on the circle or the edge of the yard

**GEOMETRY CIRCLES PLEASE**

This is just too easy. Remember that both tangents to the same circle from an exterior point are equal. so AB = AC but AC is also tangent to the small circle so AC = AD but AD is also a tangent to the circle at the right so AD = AE Since the are all equal , and AB = 15 each on...

**Math-Trig**

make a diagram showing a sideview. remember the angle of depression from the helicopter view is equal to the angle of elevation from groundview. So I have a right-angled triangle, with a height of 105 (opposite side), the adjacent side of x and an angle of 30.5 take it from there

**calc**

first of all use the rules of logs y = ln (1 - x^2)^(1/2 = (1/2) ln (1 - x^2) now ... dy/dx = (1/2) (-2x)/(1-x^2) = -x/(1-x^2)

**finance**

My interpretation of the wording first year = 47500 2nd year = 47500(1.23) third year = 47500(1.23)^2 fourth year = 47500(1.23)^2 (1.12) = .....

**Algebra 1**

You have the same base, so (8^6/8^4)(8/2) = 8^(6-4+2) = 8^4

**prealgebra**

when is .15t + 26.50 = .25t + 14.50 multiply by 100 to clean up the numbers 15t + 2650 = 25t + 1450 -10t = -1200 t = 120 minutes at 120 minutes the charge would be the same

**prealgebra**

Four times a number is 21 more than the number ----> 4x = 21 + x 3x = 21 x = 7 Anna "thought" the answer is 7 Now you can be 100% sure that the answer is 7

**Math**

Ummmh, the ratio of radius to diameter is always 1 : 2

**ALGEBRA 1**

z^-9 is the same as 1/z^9 both answers are correct

**Trigonometry/Geometry**

Start by drawing a reasonably accurate rhombus on a piece of paper. Remember a rhombus has 4 equal sides and opposite angles equal, ( A square is a special kind of rhombus, so don't use a square) cut your rhombus out with scissors. Surprisingly, you will be able to form a ...

**math formula help needed**

let her payment be p i = .065/52 = .00125 p( (1.00125^312 - 1 )/.00125 = 15000 solve for p You should get p = 78.68

**Fault in "education" - the cay(help)**

Let me understand this ! You have an assignment due on a book which you have not read or even seen. That assignment was due tonight, and you expected us to just give you the answers. Call me old-fashioned, but when I was teaching I would have called that "cheating" Y...

**math**

Use that same fantastic webpage I just gave you.

**math**

One of the best webpages available for this topic http://davidmlane.com/hyperstat/z_table.html It replaces your tables at the back of your text. enter mean of 170 enter sd of 5 a) click on 'between' and enter 170 and 180 multiply that by 60 b) what do you think?

**math**

i = .06/4 = .015 n = 4(6) = 24 What is the "future" value .... So which formula do you think you should use ? What is your equation? Let me know what you got.

**math**

You want the present value of 20 payments of 5500 at the end of each quarter for 5 years i = .08/4 = .02 n = 4(5) = 20 PV = 5500( 1 - 1.02^-20)/.02 = $89932.88

**annuities..math**

i = .06/12 = .005 n =2.5(12) = 30 amount = 100( 1.005^30 - 1 )/.005 = $3228.00

**geometry**

mmmhhhh http://www.jiskha.com/display.cgi?id=1386103063

**geometry**

let the outer segment of the 2nd secant be x then the inner segment is 28-x 8/6 = x/(28-x) 6x = 224 - 8x 14x = 224 x = 16

**algebra**

prob(2) = 1/6 prob(not 2) = 5/6 prob (four 2's out of 6) = C(6,4) (1/6)^4 (5/6)^2 = 15(1/1296)(25/36) = appr .008

**Geometry**

2.54 cm = 1 inch (official definition of inch since 1959) 1 cm = 1/2.54 inches 1 m = 100/2.54 inches 1 km = 1000(100/2.54) inches = 100000/(2.54*12*5280) miles = .62137 miles which is the same as your other definition correct to 2 decimals.

**Math**

Good Grief !! http://www.wolframalpha.com/input/?i=plot+y+%3D+ln%7CSin2X-CosX-1%7C+ First of all, if ln (something) = 0 then (something) = 1 so sin 2x - cosx - 1 = 1 or -1 easy one first: sin 2x - cosx - 1 = -1 2sinxcosx - cosx = 0 cosx(2sinx - 1) = 0 cosx=0 or sinx= 1/2 x = &...

**incorrect - math answer check please**

the interest rate is 5% per annum compounded monthly that means you get .05/12 each month, NOT .05 I did this question for you , look back to see the solution. Your solution and answers above make absolutely no sense.

**math**

value of 125000 6 months from now = 125000(1.00416666...)^6 = 128157.73 Pr value of 135000 x(1.00416666..)^6 = 135000 x = 131673.68 So both solutions show that he should take the 135000 six months from now. At he present time, the difference is worth = 131673.68 - 125000 $ 667...

**Algebra!**

#2 done the same way as the first x+y = 41 ---#1 12x + 17y = 582 ---> #2 #1 times 12 12x + 12y = 492 12x + 17y = 582 subtract them: 5y = 90 y = 18 then x = 23 23 short-sleeved and 18 long-sleeved shirts

**Go with Kuai - Algebra 1 (Reiny or Kuai)**

sorry about my arithmetic error when I copied your diagram to paper, I had point Q as (3,6) instead of (2,6)

**Algebra 1 (Reiny or Kuai)**

I did this for you , it was #5 of http://www.jiskha.com/display.cgi?id=1386029033 Ok, once more, very simple: slope PQ = (6-4/(2-1) = 2 slope QR = (6-3)/(2-8) = -3/5 So there is no right angle at Q but a rectangle must have 4 right-angles I have shown that one of them is not, ...

**Algebra 1 (Reiny or Kuai)**

in a trapezoid, one pair of opposite sides are parallel Make a sketch slope BC = (5-2)/(4-6) = 3/-2 = - 3/2 slope AD = (5-(-1))/)-2-2) = 6/-4 = -3/2 Yup, it is I didn't check for the other pair I could see that AB is horizontal, since both points have the same y value, whi...

**Algebra 1 Answer Check (Reiny or Kuai)**

#5. no, it is not a rectangle. angle P = 90° angle S = 90° but since slope PQ = 2 and slope of QR = -3/5 we don't have a right angle at Q no need to go further.

**Algebra 1 Answer Check (Reiny or Kuai)**

1. y=6 and y=-8 are parallel, they are both horizontal y=6x + 5 and y = 6x-7 are parallel, they both have a slope of 6 2. the first and third are parallel, you had that but also the 2nd and last line are parallel, both have a slope of -2 3. the 1st and 2nd lines are perpendicu...

**math**

Did you mean 7 is added to the result after dividing by 6 ? Else how can you add 7 to the divisor if the division has been done? The wording is very odd. According to my interpretation: x/6 + 7 = 4 x/6 = -3 x = -18

**Math**

1 inch ---> 6 inches 2 inches ----> 1 foot 32 inches ----> 16 feet

**math**

type it this way: f(x) = x^5 - 6x^4 + 7x^3 - 10x^2 since complex number zeros always come in conjugate pairs, there is another zero of 1-i so (x -(1+i)) and (1 - (1-i)) are factors expanded gives us: (x-1-i)(x-1+i) = x^2 - x + ix - x + 1 - i - ix + i - i^2 , but i^2 = -1 = x^2...

**math**

I found f(3) = 0 , x-3 is a factor then found f(-2) = 0 , so x+2 is a factor divided both of those and got -(2x^2-7x+3) which factored further to -(x-3)(2x-1) so f(x) = -(x-3)^2 (x+2)(2x-1) with zeros at x= -2, 1/2 and 3 , 3 being a double root

**2nd question - calculus area between three curves**

nice symmetry, should be easy to see that the x-intercepts are (c,0) and (-c,0) for both so just double the area from 0 to c area = 2∫(c^2 - x^2 - (x^2 - c^2)) dx from 0 to c = 2∫(2c^2 - 2x^2) dx from 0 to c = 2[2c^2 x - (2/3)x^3] from 0 to c = 2(c^3 - (2/3)c^3] = ...

**calculus area between three curves**

3 graphs: y = 2√x y = 3 y = (-3/2)x + 7 see: http://www.wolframalpha.com/input/?i=plot++y+%3D+2√x+%2C+y+%3D+3+%2C+y+%3D+%28-3%2F2%29x+%2B+7+%2C+2%3Cx%3C3 intersection of y = (-3/2)x+7 and y = 2√x is aprr A(2.54, 3.188) intersection of y = 2√x and y = 3 ...

**calc**

Ok, let's do it their way, (and get the same answer as I got before) Let the number of actual trees planted be k (I will now switch my original definitions to this new definition) number of trees = k , I had x+30 so k= x+30 and x = k-30 yield per acre: I had 150-3x = 150 -...

**calc**

Looks like you defined x as the number of extra trees to be planted, which is what I did as well They defined x as the actual number of trees planted. When you differentiate their equation , set it equal to zero and solve you get x = 40 the total number of trees is 40 Notice t...

**calc**

Let x be the number of additional trees planted per acre Number of trees per acre = 30+x yield per tree = 150 - 3x total = (30+x)(150-3x) = 4500 + 60x - 3x^2 d(total)/dx = 60 -6x =0 for a max total 6x=60 x = 10 So the max yield is obtained with 40 trees per acre. BUT, your con...

**Math**

first derivative: 2x = -2y dy/dx at (3,4) dy/dx = -3/4 2nd derivative: 2 = -2y( d^2y/d^2x) + (-2)(dy/dx) at the given point (3,4) 2 = -8(d^2 y/d^2 x) - 2(-3/4) 8 (d^2 y/d^2 x ) = 3/2 - 2 = -1/2 d^2 y/d^2 x = -1/16

**Geometry**

make a sketch drawing both diagonals Look at one of the triangles containing the 60° angle. Since the diagonals bisect each other, each side containing the 60° angle must be 12 inches long. The triangle must be isosceles, so each of the other angles is also 60°, an...

**Math**

I do not follow your order of exponents You will have to be much more specific by using brackets e.g. 2^3^4 done on my calculator by punching it in that way gives me 4096 (The calculator appears to evaluate from left to right and simply does (2^3)^4 = 2^12= 4096 But, what abou...

**Math Probability *Repost***

yes if the prob of winning by buying 1 ticket is 1/38760 then the prob of winning with 1000 tickets is = 1000(1/38760) = 25/969

**Math Probability *Repost***

As I stated in my previous reply to the same post .... Number of ways to draw 6 numbers from 20 is C(20,6) = 20!/(6!14!) = 38760 so prob(winner) = 1/38760

**Algebra**

width = x length > 2x Area > 2x^2

**Math**

first number --- x 2nd number --- y 2x - y = -1 or y = 2x+1 2y + 3x = 9 2(2x+1) + 3x = 9 4x + 2 + 3x = 9 7x = 7 x = 1 then y = 3 The first number is 1, and the second number is 3 check: twice the first - second = 2 - 3 = -1 , check! twice the second added to three times the fi...

**algebra**

one cut makes 2 pieces two cuts make 3 pieces ... ? cuts make 12 pieces ?

**Math Probability**

Done here http://www.jiskha.com/display.cgi?id=1385948148 Why are you switching names?

**Math**

Once again, the same kind of question as before. step1: find slope (you did that correctly and got m = -2) step2: use y-y1 = m(x-x1) , where (x1, y1) is either of the given points using (2,4) y-4 = -2(x-2) y-4 = -2x + 4 standard form has both x and y terms on the left, the con...

**Math Probability**

Joe has assumed that the same number could be drawn more than once. However,in most of these lotteries, some kind of drawing method is used, such as 20 different-numbered pingpong balls, and the order that they are drawn does not matter. Number of ways to draw 6 numbers from 2...

**MATH**

Henry had done this same question for you here http://www.jiskha.com/display.cgi?id=1385944773 why did you repost it?

**PreCal**

notice the following pattern 2^0 = 1 2^0 + 2^1 = 3 = 2^2 - 1 2^0 + 2^1 + 2^2 = 7 = 2^3 - 1 , 3 terms in sum 2^0 + 2^1 + 2^2 + 2^3 = 15 = 2^4 - 1 , 4 terms in sum ... 2^0 + 2^1 + ... + 2^9 = 1023 = 2^10 - 1 (the sum of n powers of 2 starting with 2^0 or 1, will be 2^(n+1) - 1 s...

**Calculus Please Help!!**

I assume you mean the triangle that the ladder makes with the ground and the wall. Area = (1/2)ab d(Area)/dt = (1/2)a db/dt + (1/2)b da/dt so when a= 5, b=12 , db/dt = 6, da/dt = -72/5 d(Area)/dt = (1/2)(5)(6) +(1/2)(12)(-72/5) = 15 - 86.4 = -71.4

**Maths**

or 3x9^x=81 , divide both sides by 3 9^x= 27 (3^2)^x = 3^3 3^(2x) = 3^3 2x = 3 x = 3/2 = 1.5

**MATH**

Hannah, you have had several related questions, and should be able to do these by now. Once more .... you slope is correct. Here is a method that should work for you all the time if you know the slope and a point ( let's pick the point (3,8) with slope 4/3 then (y-8)/(x-3)...

**MATH HELP**

a^(2t/3)

**Math**

Perpendicular to which line ? Did you just want a vertical line ? Try to sketch a vertical line which "cuts" across the y-axis , pretty tricky eh? So what do you think?

**Math - Algebra 2**

let y = ax^2 + bx + c for (0,-5) -5 = 0 + 0 + c, so c = -5 for (3,-6) -6 = 9a + 3b - 5 9a + 3b = -1 , #1 for (-3,-7) 9a -3b -5 = -7 9a - 3b = -2 , #2 add #1 and #2 18a = -2 a = -1/+ sub into #1 9(-1/6) + 3b = -1 -3/2 + 3b = -1 -3 + 6b = -2 6b = 1 b = 1/6 so f(x) = (-1/6)x^2 + ...

**Maths**

The first one contains a typo and makes no sense 2nd: I bet you mean: 27^(x+5) = 9^(2x-1) then ... (3^3)^(x+5) = (3^2)^(2x-1) 3^(3x+15) = 3^(4x-2) 3x + 15 = 4x - 2 -x = -17 x = 17 3rd: 8(16^(x-1) = 4^(3x) (2^3)(2^(4x-4) = 2(6x) 2^(4x-1) = 2^(6x) 4x-1 = 6x -2x = 1 x = -1/2

**Math**

y = |x^4 - 5x^2 + 4| = | (x^2 - 4)(x^2 - 1) | = | (x+2)(x-2)(x+1)(x-1) | I graphed it on Wolfram http://www.wolframalpha.com/input/?i=plot+y+%3D+%7Cx%5E4+-5x%5E2+%2B4%7C%2C+-3%3C+x+%3C+3 Notice that there are cusps at the zeros of the corresponding non-absolute function At a c...

**Trigonometry**

And I had already done this for you here http://www.jiskha.com/display.cgi?id=1385827548 This is the third time you have posted this question. Always check your previous post before re-posting

**Trigonometry**

And I had already done this for you here http://www.jiskha.com/display.cgi?id=1385827548 This is the third time you have posted this question. Always check your previous post before re-posting

**algebra 1**

slope = (4-3)/(-2-0) = -1/2 since (0,3) is the y-intercept y = (-1/2)x + 3 ...... all done

**MATHS**

I suggest you Google something like "Chinese Remainder Theorem" and I assume you know about modular arithmetic since I will be using properties of modular arithmetic so we have z = 1 mod 6 z = 1 mod 7 z = 7 mod 8 z = 7 mod 11 But, in the Chinese Remainder Therorem we...

**math**

I find it hard to see why this is difficult. Since there is no interest Just subtract the rebate, then divide that answer by 60.

Pages: <<Prev | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | **16** | 17 | 18 | 19 | 20 | 21 | 22 | Next>>