Monday

October 20, 2014

October 20, 2014

Total # Posts: 25,933

**Algebra**

as usual, first just clear fractions: (n+9)(7) = 6(d+9) (n-7)(3) = 2(d-7) 7n+63 = 6d+54 3n-21 = 2d-14 7n-6d = -9 3n-2d = 7 Now can you solve for n and d?
*September 21, 2014*

**Algebra**

Just put the words into symbols. If the original fraction is n/d, then (n+9)/(d+9) = 6/7 (n-7)/(d-7) = 2/3 Now just solve for n and d.
*September 21, 2014*

**math**

If the base of the rectangle has length 2x, and height y, the area is a = 2xy = 2x√(1-x^2/16)(4) = 2x√(16-x^2) da/dx = 4(8-x^2)/√(16-x^2) so, max area occurs at x=√8, and the rectangle is 2√8 by √2
*September 21, 2014*

**AP Calc. AB**

Clearly A is not continuous at x = -1, since the denominator is zero. The domain of √u is u >= 0. So, we need x+6 >= 0 The domain of sin x is all reals, so it doesn't affect the result. we know that lim sin(x)/x = 1, so sin(2x)/(2x) is 1. So, lim sin(2x)/x = 2...
*September 21, 2014*

**Algebra**

The only question I see is whether x^3-2x^2-1+2 = 0 For some values of x, it is. I suspect a typo, since you have no x term, and two constant terms. Why not fix the typo and then ask your real question?
*September 21, 2014*

**Math.**

x - 8.77 = 23.40
*September 21, 2014*

**math**

2.3x = 48.00
*September 21, 2014*

**Math**

20*27 = ?
*September 21, 2014*

**Math**

100/200 = x/53.40
*September 21, 2014*

**Math**

what is the difference between 10 and 6? It is 10-6, or 4. So, the difference here is just x = 39.50 - 23.50
*September 21, 2014*

**math**

clearly (0,5) is is a set of x values, since x is in that interval. I'm sure it is just to restrict us to a single period of 2π. 1+x <= f(x) <= 3+sin πx as x->2, 1+2 <= f(x) <= 3
*September 21, 2014*

**math**

#1: c = 9.95 + .10m #2: c = 12.95 + .08m
*September 21, 2014*

**maths**

In triangles adb and adc, angle adb = angle adc bd = dc ad = ad So, the triangles are congruent, meaning ab = ac so abc is isosceles.
*September 21, 2014*

**Algebra**

correct
*September 21, 2014*

**math**

If the digits are a and b then 10a+b = 8(a+b) 10a+b - 45 = 10b + a The number is 72
*September 21, 2014*

**Algebra 2 (Please, help me!)**

well, it just means that all points have become 1/3 as far away from the origin as they were. Just divide all the coordinates by 3: (9,-6) -> (3,-2) and so on
*September 21, 2014*

**math**

the area grows as the square of the length ratio. So, the sides are in the ratio √9:√4 = 3:2. So also are the perimeters.
*September 21, 2014*

**trigonometry**

as usual, draw a diagram, and review your basic trig function definitions: tan θ = 5100/12000 So, θ = arctan(51/120)
*September 21, 2014*

**Physics help ASAP**

Suppose you are visiting a planet in a distant part of the galaxy.To determine the acceleration due to gravity on this planet, you drop a rock from a height of 55 m. The rock strikes the ground 1.9 s later.How many times greater is the acceleration due to gravity on this ...
*September 20, 2014*

**Physics**

A baseball is thrown upward with an initial speed of 35 m/s. What is the speed at t = 2 s?
*September 20, 2014*

**physicas**

A baseball is thrown upward with an initial speed of 35 m/s. What is the speed at t = 2 s?
*September 20, 2014*

**Physics**

A basketball is shot from an initial height of 2.4 m with an initial speed (v0 = 12 m/s) directed at an angle (35 degrees) above the horizontal. Additional information: Height of the basket is 3.05 m Find how far away the player is standing.
*September 20, 2014*

**math**

generally true, but the right angle is not at exactly 1:15, because the hour hand has also moved 1/4 of the way from 1 to 2. after m minutes, the minute hand has moved m/60*360 = 6m° the hour hand has moved to 30+m/2° So, we need to find m when 6m = 30 + m/2 + 90 11m/2...
*September 20, 2014*

**Operating system**

so, you expect us to do your research? I'd start with google, and then start reading.
*September 20, 2014*

**Algebr**

correct
*September 20, 2014*

**math**

the difference between two number m and n is m-n. So, you are comparing -14 and -10. The difference is -4 - (-10) = -4 + 10 = 6 That is, he lost 6 more ounces this year than last year.
*September 20, 2014*

**Pre-Cal**

but, at (1,-1), x^2+y^2 = 2 The maximum occurs when x = 2/√29 y = -5/√29
*September 20, 2014*

**math**

5h^(2/5) = 3645/5 h^(2/5) = 3645/25 h^(2/5) = 3^6/5 h^(1/5) = 27/√5 h = (27/√5)^5 That's an unusual result. I suspect a typo. If so, fix it and follow the same logic to arrive at the correct answer.
*September 20, 2014*

**Algebra**

you are correct.
*September 20, 2014*

**Math**

(b) recall that the vertex of a parabola is at t = -b/2a. In this case, that's 32/32 = 1. (a) just plug in t=1.
*September 20, 2014*

**Algebra 2--Please, help me!**

#1 ok #2 ok #3 right value, but not scientific notation #4 ok #5 Well, if it is a function, then no last name maps to more than one age. What do you think? #6 r(d) 75.00-3.50d I think you can answer the other parts of this one, no?
*September 20, 2014*

**factorise completely**

a(2x-3y) + (2x-3y) (a+1)(2x-3y)
*September 20, 2014*

**math**

Just start at -8 and start listing the odd numbers: -7 -5 -3 -1 1 3 5
*September 20, 2014*

**Math**

5/8 + 1/2 = 9/8 Only 7/8 were sick, so 2/8 had both
*September 20, 2014*

**Math**

13000/(1 - 2/5 - 1/6) = ?
*September 20, 2014*

**Math (Equation of a circle)**

clearly the radius is 2, since the center is at y=2. So, the equation is (x-3)^2 + (y-2)^2 = 4
*September 20, 2014*

**Math**

a^74/a^33 = 26p/-2p = -13 so, a = (-13)^(1/41)
*September 20, 2014*

**math**

x <= -2 has the filled dot at -2, but the shading continues all the way to the left. No idea what all those other values are supposed to be.
*September 19, 2014*

**Business math**

You need to find x where 12400(.042) = x(.0385)
*September 19, 2014*

**math**

to find how many times greater 6 is than 3, divide 6 by 3. So, for your birds, divide (13 9/10) by (3 1/2). Your answer 278/70 is the correct value, but it could be simplified to 139/35. Since 3.9714 is only approximate, it is hard to recover the fraction. Both your answers ...
*September 19, 2014*

**Math Help**

just replace all the x's with (x-1): f(x-1) = 4(x-1)^2 + 3(x-1) - 3 I assume you can simplify that.
*September 19, 2014*

**Algebra 2**

r(d) = 75.00 - 3.50d
*September 19, 2014*

**Algebra 2**

#3 is the correct value, but it is not scientific notation. The others are ok.
*September 19, 2014*

**Math**

Do a little simplification first. As long as x≠5, (x^2-25)/(x-5) = (x-5)(x+5)/(x-5) = x+5 So, what you have is, f(x) = x+5 if x <= -1 2x-3 if x > -1 So, since 4 > -1, f(4) = 8-3 = 5 And, since -1 <= -1, f(-1) = -1+5 = 4
*September 19, 2014*

**math skill sheet 777**

add up the values of 1 of each coin: 1+5+10+25 = 41 Now, how many 41's in 205? That's how many of each coin you have. so, now you can total up how many coins you have in total.
*September 19, 2014*

**Math help**

By "sum" I assume you mean the sum of three numbers in any row, with the center in each row. One way is surely to place the middle number (29) in the center. Then in pairs place the other numbers on ends of diameters, increasing on one end, decreasing on the other, ...
*September 19, 2014*

**Math**

No, D has the solution y=0 6y-2 = 2y-2 4y = 0 y=0 C is the one you want: 7x+5 = 7x+5 Both sides represent the same value, so any solution of the left side is also a solution on the right side.
*September 19, 2014*

**Pre-Calculus Questions**

(1) The slope is -6/6 = -1 So, in point-slope, we have y-3 = -1(x+5) Now massage that into slope-intercept form. Clearly, when x=0, y = -3 Since y = (x-3)(x+1), y=0 when x is -1 or 3. So, draw a parabola with those roots, which opens upward. Recall that the vertex occurs ...
*September 19, 2014*

**physics**

x(t) = Xo + Vot - 1/2 at^2 So, (5Vo - 25/2 a)-(4Vo - 16/2 a) = 100 (8Vo - 64/2 a)-(7Vo - 49/2 a) = 120 so, Vo = 70 a = -20/3 Now just figure x(20)-x(19)
*September 19, 2014*

**Math**

Just consider each ball's chances as it is drawn: 3/15 * 2/14 * 1/13 * 12/12 * 11/11 * ... = 1/455 Note that after all the red balls are drawn, there is a 100% chance that the rest will be white. Also, the order does not matter. If the order were WWRWWRWR the chances would...
*September 19, 2014*

**Algebra 2 Answer Check**

#3: Typo? I get 13xy #5: -2x^4y^7 / x^5 = -2y^7/x Now cube that. And watch that - sign
*September 19, 2014*

**Math**

Clearly a = 250000 r = 1/5 Now just use your sum formula.
*September 19, 2014*

**MATHS**

since sec^2 θ - tan^2 θ = 1, you have -8(sec^2 θ - tan^2 θ) = -8 Better review your basic identities. The most important is, of course, sin^2 θ + cos^2 θ = 1 divide through by cos^2 and you have tan^2 θ + 1 = sec^2 θ
*September 19, 2014*

**Math**

Surely you can determine T1 ?? Clearly d = -2b So now just apply your formulas.
*September 19, 2014*

**Algebra 2**

well, f(-x) = -x/(-x-1) = x/(x+1) ≠ -f(x) so no symmetry about (0,0) Also, f(-x) ≠ f(x), so no symmetry about the y-axis f^-1(x) = x/(x-1), so there is symmetry about the line y=x. See http://www.wolframalpha.com/input/?i=inverse+x%2F%28x-1%29
*September 19, 2014*

**Algebra**

Better review your symmetry section. No ideas on any of them?
*September 19, 2014*

**Math**

Ah. Finally! a(1-3^8)/(1+3) = -3280 -1640a = -3280 a = 2
*September 19, 2014*

**Math**

If the radius of the base is r, then tan(62/2) = r/8
*September 19, 2014*

**math**

5P2 = 20
*September 19, 2014*

**Math**

√-1 = i √-81 = 9i √-36 = 6i The syntax is garbled.
*September 19, 2014*

**Algebra**

(16x^2+1)(x^2+4) = 0 No real roots, but easy-to-find complex roots
*September 19, 2014*

**Algebra**

x(x^2+6x+10) = 0 Now use the quadratic formula. There is only 1 real root.
*September 19, 2014*

**Pre-Calculus**

of course it's not found - the photo is a file on Cynthia's computer!
*September 19, 2014*

**calculus**

well, surely you did some of the steps. What did you find? We can help fill in any missing info.
*September 19, 2014*

**calculus**

wolframalpha is your friend: http://www.wolframalpha.com/input/?i=8x^3-2x^4
*September 19, 2014*

**calculus**

first: coordinates, not coordination next, a hint: Inflection points occur where f"(x) = 0 and f'(x) ≠ 0
*September 19, 2014*

**Math Precal/Trig**

3^7 = 2187, so you have 7(1+2187)/4 = 3829 which is true. But, as I recall, that does not answer the question in the problem as you originally posted it. I suspect that you did not check for that typo.
*September 18, 2014*

**Math (Exponents)**

Do you mean 4*10^0 + 7*10^-1 + 2*10^-2 + 8*10^-3? If not, maybe you could splain just what you do want.
*September 18, 2014*

**Math-The chain rule HELP**

y = 1/u dy/dx = dy/du * du/dx = -1/u^2 * 6x = -6x/u^2 = -6x/(3x^2+5)^2
*September 18, 2014*

**math**

I'd start with the biggest book: 200 = 100+100 200 = 100+50+50 200 = 100+50+10+10+10+10+10 and so on, breaking each possible book down into its parts. Watch out for duplicate entries.
*September 18, 2014*

**trig**

Review your basic trig functions. As always, draw a diagram. If the distance is x, tan65° = x/30
*September 18, 2014*

**Algebra2**

Since the peak height of 15 was reached at t=3, h(t) = a(t-3)^2 + 15 Since h(0) = 7, a = -8/9, so h(t) = -8/9 (t-3)^2 + 15 Now you can answer the questions
*September 18, 2014*

**Math**

Surely you can determine T1 ?? Clearly d = -2b So now just apply your formulas.
*September 18, 2014*

**Math**

no diagrams here, but a google on vectors dot product will turn up many discussions and diagrams.
*September 18, 2014*

**Math**

t1 = 7/4 d = -3/4 Tn = 7/4 - 3/4 (n-1) ...
*September 18, 2014*

**Math**

T2-T1 = 1/20 T3-T2 = 1/12 So, not arithmetic T2/T1 = 5/4 T3/T2 = 4/3 So, not geometric
*September 18, 2014*

**Math**

I suspect a typo. Moving right along, S8 = a(1-r^8)/(1-r), so just plug in your values.
*September 18, 2014*

**math**

It would certainly be easier to analyze the situations if you had not run them all together into one long sentence. Take the last one. Clearly the net charge is 12(0 + 1 + (-1)) = 12(0) = 0 Surely you have some thoughts on the others. Don't get rattled by all the words; ...
*September 18, 2014*

**Math**

Clearly, the nth winner gets 250000 * 0.20^(n-1) This is just a geometric series with a = 250000 r = 1/5 So, just apply your seies formulas
*September 18, 2014*

**Algebra**

Assuming a shift to the right, that would be g(x) = (x-2)^2/5 See http://www.wolframalpha.com/input/?i=plot+y+%3Dx^2%2C+y%3D%28x-2%29^2%2F5+for+-3%3C%3Dx%3C%3D5
*September 18, 2014*

**math**

I suspect the t was supposed to be a y, making things 3p(x-y) - (x-y) (3p-1)(x-y)
*September 18, 2014*

**algebra**

well, that would clearly be 36 + 43e^(-0.058*14)
*September 18, 2014*

**math**

That means the exterior angles are 40, so there are 9 sides.
*September 18, 2014*

**Math algebra**

probably OOUUUUCCCHHH!!
*September 18, 2014*

**sixth grade math**

Odd - you got #1 correct, but missed the other two. 1 5/6 * 2/3 = 11/6 * 2/3 = 22/18 = 11/9 7/8 * 3 1/3 = 7/8 * 10/3 = 70/24 = 35/12 How ever did you arrive at those answers? #2 I could call a typo, but not #3.
*September 17, 2014*

**Chem**

wow - can't believe I mangled those digits! But you noticed that on your own, right, Jessica? :-)
*September 17, 2014*

**Chem**

the density is evidently 29.3g/(16.7-14.2)ml = 23.9/2.5 = 9.56 g/cm^3 Find that in your table of materials
*September 17, 2014*

**Math**

90 boys like soccer, so 150 boys like basketball Assuming those were the only two sports in the survey, that means 240 boys were surveyed. So, 240 girls were surveyed. That means 210 liked soccer and 30 liked basketball.
*September 17, 2014*

**math**

Who knows what the names are? But, doing the algebra, 2x^2+3x+1 + x^2+5x+8 = 3x^2+8x+9
*September 17, 2014*

**Math**

The LCM is the product if they have no factors in common (relatively prime) Now it should be easy to pick the proper pairs. In fact, since they actually gave you the LCM's, it's just a matter of seeing whether the two numbers multiply to give the indicated LCM!
*September 17, 2014*

**Algebra**

Assumiong all the tiles are to be used, find the GCF(45,75,90). That is 15 45 = 3*15 75 = 5*15 90 = 6*15 So, he can make 15 stones, each with 3 red, 5 yellow a
*September 17, 2014*

**science/math**

How ever did you get a negative number? I'd assume we are using the same positive acceleration, starting from 50 mph! assuming constant acceleration, then since the velocity changed by 88ft/s in 8 seconds, a = 11 ft/s^2 Now to find v, just recall that v(t) = Vo + at Just ...
*September 17, 2014*

**Algebra! please help**

first, complete the squares: x^2+x + y^2-6y = -9 x^2+x+(1/4) + y^2-6y+9 = -9 + 1/4 + 9 (x + 1/2)^2 + (y-3)^2 = 1/4 Now all should be clear. See http://www.wolframalpha.com/input/?i=x^2%2By^2%2Bx-6y%2B9%3D0
*September 17, 2014*

**business in mathematics**

After 10 5/12 years, the amount is 9500(1 + .055/4)^(4*10.417) Not sure how the periods are divided into pieces.
*September 17, 2014*

**Algebra 1**

what are the numbers moving away from 0? Surely you can figure out how many stairs she has to climb. She has to go down 4, back up to 0, and then up another 4, then back to 0.
*September 17, 2014*

**Algebra**

3(a-2) = a 3a-6 = a 2a = 6 a = 3
*September 17, 2014*

**Physics Grade 12**

solve for t when the distances are equal: 0 + 1.1t^2 = 12.2t Now recall that since she started from a dead stop, s = 1/2 at^2 v = at
*September 17, 2014*

**Algebra**

Assuming the ) means a 0, we want 125 + 0.15x = 75 + 0.40x
*September 17, 2014*

**math**

If the rate is constant, then t = md+b Now plug in two pairs of values, say the first two. 8 = 40a + b 6 = 56a + b So, a = -1/8 and b=13 t = -1/8 d + 13 Now check the other two pairs of values to make sure they agree.
*September 17, 2014*

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