Monday

March 2, 2015

March 2, 2015

Total # Posts: 29,297

**Math**

k^-3 = 1/k^3 So, you want 1/k^3 = 1/256 k^3 = 256 Now, 256 = 2^8, so k = 2^(8/3) = 2^2 * 2^(2/3) = 4∛4 Hmmm. we got trouble. (a) and (b) are out. 4^-3 = 1/4^3 = 1/64 64^-3 = 1/64^3 = 1/4096 I think that 1/256 is a mistake. Or, the -3 is a mistake. 16^-2 = 1/16^2 = 1/256 ...
*January 7, 2015*

**Math**

wow - use run-on sentences much? If the base is x by y and the height is z, just break the area into rectangles lateral area: 2(xz+yz) total area: 2(xz+yz+xy) Now just plug in your numbers. You didn't say which was which.
*January 7, 2015*

**math**

2/3 = 16/24 3/4 = 18/24 So, what do you think is in between them?
*January 7, 2015*

**Math**

5^13 = 5^6 * 5^7 The powers on the right can be any two numbers which add up to 13.
*January 7, 2015*

**physics**

how long does it take the dart to fall 0.32 m? 4.9t^2 = 0.32 with that t, find the distance is 13.5t
*January 7, 2015*

**Algebra 1**

2(x+y) = 100 But, y = 3x+2, so 2(x+3x+2) = 100 ...
*January 7, 2015*

**math**

20*2πr = 45*60 must be a wind turbine.
*January 7, 2015*

**math**

6C2 = (6*5)/(1*2) = 15
*January 7, 2015*

**Algebra**

remember that log x^n = n*log x So, log(4)(3x + 4)^5 = 15 5log(4)(3x + 4) = 15 log(4)(3x + 4) = 3 3x+4 = 4^3 = 64 3x = 60 x = 20 Expanding (3x+4)^5 would not help, because then you just have a polynomial, but the log of a sum cannot be simplified. log(x^2+3) is not log x^2 + ...
*January 7, 2015*

**Math**

Assuming you mean (1+2x)/(x+4) = 3/(x-1) (1+2x)(x-1) = 3(x+4) 2x^2 - x - 1 = 3x + 12 2x^2 - 4x - 13 = 0 Now it's just a regular old quadratic equation to solve. Note that right from the beginning you have to exclude -4 and 1 from the domain.
*January 7, 2015*

**Math**

2x^2-2 = 2(x-1)(x+1) 2x^2-8x+6 = 2(x-1)(x-3) Now rewrite your fractions with the factors, put all over a common denominator of 2(x-1)(x+1)(x-3) and simplify the numerator. Probably something will cancel out. Non-permissible values are those that make any denominator zero.
*January 7, 2015*

**Math**

#1 I haven't followed the argument through yet, but I think if you play around with 0 < a < 1 (x+1)^a <= (x+1)^1 x^a + ax^(a-1) + ... + ax + 1 <= x+1 things will work out.
*January 7, 2015*

**MATHS**

well, (42)^2 - (38)^2 - (17)^2 = 31 so that should get you started...
*January 7, 2015*

**maths**

well, you have a = π/2 r^2 θ So, plug in a and r to find θ, and then you know that the arc length s = rθ Or, do it at one fell swoop: s = r(2a/(πr^2)) = 2a/πr
*January 7, 2015*

**Maths trigonometry**

secAcotB-secA-2cotB+2=0 secA(cotB-1) + 2(cotB-1) = 0 (secA+2)(cotB-1) = 0 Now it should be clear what the angles are.
*January 7, 2015*

**Math**

yes, as long as x≠1 (1-x) = -(x-1), so you have -x^2(x-1) ------------- (2x-3)(x-1) and the x-1 factors cancel.
*January 7, 2015*

**Algebra**

well, does it work in both equations x-3y = -5-3*2 = -11 ≠ 1 So, I'd say a resounding NO.
*January 7, 2015*

**Algebra**

the 2nd equation says that y = 2x-4 So, substitute that into the 1st to get 2x + 4(2x-4) = -2 Surely you can solve that, and then find y ...
*January 7, 2015*

**Math**

p' = 1-p that should get you started.
*January 6, 2015*

**algebra**

11x + 11(x+1) > 100 11(x+1) + 11(x+2) < 200 22x > 89 22x < 167 4.04 < x < 7.59 So, the numbers can be 55 66 77 66 77 88 77 88 99
*January 6, 2015*

**math**

I can't find the integers until you clarify what the difference between five times the greater even integer is 14 means
*January 6, 2015*

**Math**

To find the x-intercept, set y=0 and you have 1.8x = 6.3 x = 3.50 Now do similarly to find the y-intercept. Set x=0.
*January 6, 2015*

**math**

The wall is 174 x 66 x 6 inches. That is 29 x 16.5 x 3 bricks. If we have to round up (no partial bricks reused), then that is 29 x 17 x 3 = 1479 bricks.
*January 6, 2015*

**PHYSICS NEED HELP ASAP**

157-75 = 82 km/hr = 22.78 m/s -22.78m/s ----------- = 3.25 s -7.00 m/s^2 so, now just use your motion formula. 157 km/hr = 43.61 m/s, so s = Vo t + 1/2 at^2 and plug in your numbers.
*January 6, 2015*

**math**

You know that the sets of numbers have to range from 2 to 8 to satisfy the max and range requirements. Half of them must be greater than 5 and half must be less than 5. 6 must occur most frequently. So, starting with a small set, we could start out with 2 5 6 6 8 Since there ...
*January 6, 2015*

**hvac**

Assuming a constant voltage, then since E = IR is constant, (1.2)(240) = I(540) Now it's easy to find the new current.
*January 6, 2015*

**Finite Math**

just solve for r in 24000(1+r)^5 = 34616
*January 6, 2015*

**math-algebra**

yes, (3a^5)^2 = 9a^10 6x^2 * 12x^3 = 72x^5 Why did you assume x=5?
*January 6, 2015*

**Math**

well, 10x^2+3x-1 = (5x-1)(2x+1) now the rest is a cinch.
*January 6, 2015*

**math**

If there are x quarts of 2% fat, then the rest (40-x) is 7%. So, just add up the fat content: .02x + .07(40-x) = .05(40) x = 16 Looks like (B) to me. You can actually get the right answer without even doing the math. C and D are clearly out, since the total is not 40 quarts. ...
*January 6, 2015*

**Bosaso**

You can do all kinds of fun Z table stuff at http://davidmlane.com/hyperstat/z_table.html
*January 6, 2015*

**math**

9.5 * 11.00 * 1.07 = ?
*January 6, 2015*

**physics**

Let the two forces be ax and by a^2+b^2 = 25 a^2 + b^2 - 2abcos120° = 37 or a^2+b^2+ab = 37 ab=12 So, it looks like the two forces are 3kN and 4kN
*January 6, 2015*

**maths**

I have a bit of trouble deciphering just what you mean, but my best guesses are 4x + 4x + 2-3y+8 = 8x-3y+10 or 12x or 3(2-3y+8) = 30-9y
*January 6, 2015*

**physics**

conserve momentum: 70*(+5) + 5(-20) = (70+5)v v = +10/3
*January 6, 2015*

**math**

If the bottles numbered w,x,y,z respectively, then we have w+x+y+z = 20840 w = 8120 y = 3960 x = y+2000 Now you can solve to find z.
*January 6, 2015*

**math**

GCF(30,48,72) = 6
*January 6, 2015*

**math**

clearly a painter can paint 1/180 of the job in one day. So, 20 painters can paint 20/180 = 1/9 of the job in a day, making the total 9 days. So, it takes 3 days less. Not also that you could reason that if the number of painters is increased by a factor of 5/4, the time taken...
*January 5, 2015*

**Physics**

since c=18, r = 18/2pi Now look at the fountain sideways. The height h can be found by noting that h/r = tan 55.0° Now just figure h.
*January 5, 2015*

**math**

n = 5*35
*January 5, 2015*

**geometry**

The height is 24tan63° + 24tan38°
*January 5, 2015*

**math**

hey - let's learn the distributive property! 6x6 = (5+1)x6 = 5x6 + 1x6 = 30+6 = 36
*January 5, 2015*

**math**

1+2 = 4-1
*January 5, 2015*

**Math**

well, we have aq = 2(pq), so 7x+6 = 2(3x+5) x = 4 ab = 3(pq) = 3(17) = 51
*January 5, 2015*

**Math**

((x + 2)/5) + ((3x - 4)/10) 2(x + 2)/10 + (3x - 4)/10 (2x+4 + 3x-4)/10 5x/10 x/2 I think you forgot to divide by 10 at the end.
*January 5, 2015*

**Math problem solving**

Clearly the maximum area is when four of the sides of the octagon are along the sides of the square. Thus, that leaves us with four unused triangles, each of side s where s/√2 + s + s/√2 = 750 s = 750/(1+√2) The area of each such triangle is thus (750/(1+&#...
*January 5, 2015*

**Math**

Looks like 12 and 15 to me
*January 5, 2015*

**exponents ,factor,fraction**

is there supposed to be a "c" in the expression? Whatever, just plug in the numbers for the letters and evaluate. Show your work in case of trouble.
*January 5, 2015*

**distance**

I get |2+9/4|/√(1/16 + 1) = (17/4)/√(17/4) = √17/2 To see how, take a look at http://en.wikipedia.org/wiki/Distance_between_two_straight_lines
*January 5, 2015*

**Math**

20+8y-9y-21 = -y-1 Now check the others: 2(10+4y-7y-19) = 2(-3y-9) = -6y-18 Nope and so on Hint: try grouping for #D
*January 5, 2015*

**algebra 1**

well, did you try actually checking the possibilities? 21 > 16+2 yes 21 < 16+5 no and so on for the others
*January 5, 2015*

**Mathematics**

ln u^n = n * ln u ln u*v = ln u + ln v ln u/v = ln u - ln v Better review the basic properties of logs.
*January 5, 2015*

**algebra**

I assume you mean +17/22 though "opposite" is a vague term with no precise mathematical meaning.
*January 5, 2015*

**Solid mensuration**

since a = 1/2 r^2 θ, just plug in π/3 and 6, and calculate a = (1/2)(36)(π/3) = 6π
*January 5, 2015*

**math, solving Oblique Δ**

A+B+C=180°, so C=115° Now use law of sines: b/sin49° = c/sin115° = 10/sin16° #2: sin88°/8 = sinB/7, so B = 61° or 109° But, since A=88°, B cannot be 109°, so there's no ambiguous case here. Now you know A and B, so you can find C and...
*January 5, 2015*

**algebra**

You just want to find x/y. I'll do #3, as the first two are trivial. xa+xb = yc+yd x(a+b) = y(c+d) x/y = (c+d)/(a+b)
*January 5, 2015*

**algebra**

the amount of gold in each alloy is the %age times the total mass: .10x + .30y
*January 5, 2015*

**math**

You have the answer. Did you guess it, or calculate it? You know that even numbers are multiples of 2 (2k), so odd numbers are of the form 2k+1. So, you want 2k+1 + 2k+3 + 2k+5 - (2k+3) = 50 4k+6 = 50 4k = 44 k = 11 So, the numbers are 23,25,27
*January 5, 2015*

**Mathematics**

just figure the difference between the outside and inside volumes: V = πr^2 h, so you want π(10.4+0.8)^2(25) - π(10.4^2)(25) = 25π(11.2^2-10.4^2) = 432π
*January 4, 2015*

**Calculus**

If the balloon is at height h, then the distance z from the child to the balloon is z^2 = h^2 + 40^2 When h=30, z=50 So, now we want dz/dt when h=30 2z dz/dt = 2h dh/dt Just plug in z=50 and h=30 and dh/dt=5 and solve for dz/dt
*January 4, 2015*

**Algebra I**

as with all word problems, translate the words to symbols. Then you have equations which can be solved. If there are a adult and c child tickets, you have two sets of facts: the number of tickets and their cost. c + a = 64 1.00c + 2.50a = 109.00 Now you can use your math ...
*January 4, 2015*

**computer science check**

The above comment refers to the actual syntax of the program. During the design, however, it is quite common to write the calls first, as that sets up the program flow of logic. Then the function definitions fill in the details.
*January 4, 2015*

**computer science check**

The languages vary, but in the strictest case, functions must be defined before they can be called, so A is my choice.
*January 4, 2015*

**physics**

they absorb most light except in the orange wavelengths, which they reflect back to our eyes. Now, as to the physical/chemical properties of the "carrot" molecules which cause that behavior, I have no clue.
*January 4, 2015*

**Pre-Calc**

well, geez. when t=8, y=33+30cos(0) = 63 Isn't that what you wanted, the max height at t=8?
*January 4, 2015*

**Pre-Calc**

since cos(kt) has its max at t=0, and you want your max at t=8, then using your correct amplitude and period, we have y = 33 + 30cos((pi/8)(t-8)) So, now just plug in t=5 to answer the question. You can see the graph at http://www.wolframalpha.com/input/?i=33%2B30cos%28%28pi%...
*January 4, 2015*

**Algebra 1**

visit calc101.com and click on the "long division" button. It will show all the details.
*January 4, 2015*

**Pre-calc/Trig**

well, recall that a parabola with vertex at (h,k) is y-k = a(x-h)^2 and for the focus, take a peek at http://www.purplemath.com/modules/parabola.htm
*January 4, 2015*

**Trig/Precalc**

(a) Try using the product-to-sum formula cos(a)cos(b) = 1/2 (cos(a-b)+cos(a+b)) (b) We have tan x/2 = (1-cosx)/sinx tan 15 = (1-cos30)/sin30 = (1-√3/2)/(1/2) = 2-√3 sin15 = √((1-cos30)/2) = √((1-√3/2)/2) = √(2-√3)/2 sin15 = √((1+...
*January 4, 2015*

**Pre-calc/Trig**

(a) as y increases, x increases, so it opens to the right
*January 4, 2015*

**math**

Since P(x) = R(x)-C(x) P'(x) = R'(x)-C'(x) max profit occurs where R'(x) = C'(x) Since you have R' and C', you can see that C(x) = x^3-59x^2+1315x + 5000 R(x) = 1000x-2x^2 + k no idea what k is, since you don't specify what R is for any ...
*January 4, 2015*

**Errrr.**

billy: "no" to which question? If you mean "no, he does not have to follow the grid (that is, travel only horizontally or vertically)," then Reiny's comments (Thanks for stepping up, Reiny) solve the problem If you mean "no, he cannot travel ...
*January 4, 2015*

**Math**

did he have to follow the grid, or could he take diagonal shortcuts?
*January 4, 2015*

**Math**

t = s+8 (s-3) = 2 + (t-3)/3 Now just solve for t. s = t-8, so (t-8-3) = 2 + (t-3)/3 t-11 = 2 + (t-3)/3 t-13 = (t-3)/3 3t-39 = t-3 2t = 36 t = 18
*January 4, 2015*

**Maths**

10y+x = 9(y+x)
*January 4, 2015*

**Algebra 1**

x+y = 10 x = 2/3 y Surely you know that 4 is 2/3 of 6 3 is clearly not 2/3 of 7 What do you care about 2/3 of 10? That was not part of the problem. The key to word problems is taking the given facts and expressing them in math symbols. It appears that you did not do that, but ...
*January 4, 2015*

**Derivative**

∫(4x^2+3)/x^2 dx = ∫4 + 3x^-2 dx And you know that ∫x^n = 1/(n+1) x^(n+1) (b) is the same thing. Just expand into a polynomial, then integrate the powers term by term. If you have no foundation in derivatives, it's curious that you've been assigned ...
*January 4, 2015*

**maths**

Just recall the power rule. y = x^n y' = n x^(n-1) (a) y' = 3(2x)-3(1) = 6x-3 For (b) and (c), just expand the polynomials, do the division as required, and then apply the power rule for each term
*January 4, 2015*

**Derivative**

g(x) = 5x^6 - 3x^-2 Just apply the power rule 3 times to get g(3)(x) = 5(6*5*4x^3) - 3(-2)(-3)(-4)x^-5 = 600x^3 - 72x^-5 Now take that two more steps for g(5)(x)
*January 4, 2015*

**Maths**

just use your facts about such sequences: a+5d = 48 6/2(a + a+5d) = 300 Now just solve for a and d.
*January 4, 2015*

**math**

<2 = 180-115 = 65 co(<2) = 90-65 = 25 or, make a general rule for the complement of any angle's supplement: 90-(180-x) = x-90 115-90=25
*January 4, 2015*

**Math**

Since 65 = 5x13, try that to see whether it fits the required perimeter. Only A and D could even possibly be a choice.
*January 3, 2015*

**algebra word problem**

just solve the equation when y=0. Just a normal quadratic solution.
*January 3, 2015*

**Geometry**

since AC=BD, 8x-10 = 2x+20 Now solve for x and evaluate BD=2x+20
*January 3, 2015*

**Geometry**

No, because 2/3 (x-6) = 2/3 x - 4
*January 3, 2015*

**Geometry**

2y+3x=6 has slope -3/2 So, the line you want has slope 2/3 ow you have a point and a slope, so the new line is y-5 = 2/3 (x-6)
*January 3, 2015*

**algebra**

well, just plug in 7a for all the x's: f(7a) = 3(7a)^2 + 8(7a) + 6 Now just evaluate the coefficients of powers of a.
*January 3, 2015*

**constitution**

Hmmm. How about <PRE> in upper case? </PRE>
*January 3, 2015*

**constitution**

let's see what <pre> text can look like </pre>
*January 3, 2015*

**math**

so ...
*January 3, 2015*

**math**

32x^2+9y^2=324 3y^2-x^2=3 Since 3y^2 = x^2+3, we have 32x^2 + 3(x^2+3) = 324 I think you can solve that fairly easily, right? The intersections are at x=±3, y=±2. See the graphs at http://www.wolframalpha.com/input/?i=plot+32x^2%2B9y^2%3D324%2C+3y^2-x^2%3D3
*January 3, 2015*

**physics**

A = (3.5,3.5) B = (6.1,-3.5) C = (-2.0,-3.5) Now just add up the (x,y) components and convert back to magnitude and direction form.
*January 3, 2015*

**Calculus**

∫csc x cot^2 x dx = ∫csc x (csc^2 x -1) dx = ∫csc^3 x dx - ∫csc x dx You probably have handy the form for ∫csc x dx, and you can use the power reduction formulas for ∫csc^3 x dx, or note that d/dx (cscx cotx) = -csc^3 x - csc x cot^2 x
*January 3, 2015*

**CALC AB**

profit is revenue minus cost, or x*p(x) - c(x) = x(18-x/400)-(820+5x+0.01x^2) = -0.0125x^2 + 13x - 820 That's just a parabola, with its vertex at x = -b/2a = 520 work #2 the same way. Figure a quantity and a price in terms of x, the number of $10 rebates. Then, revenue is ...
*January 3, 2015*

**Math Linear Equations**

c'mon. The lines intersect where the functions are equal: -2 = 3x+1 Now find x, and you know darn well that y = -2, since one of the lines is y = -2 for any x. y = -2 is a function of x, like any other linear function. It just so happens that no matter what x is, y = -2! y...
*January 2, 2015*

**AP CaLC. AB**

Assuming you know that max/min problems involve finding when f'(x)=0, #1 If the base of the ladder is x feet from the fence, and the height up the wall is y, then the length z of the ladder is z^2 = (x+7)^2 + y^2 and using similar triangles, y/(x+8) = 8/x Now you can ...
*January 2, 2015*

**equation and inequalities**

In n games, he will chew 17n sticks of gum
*January 2, 2015*

**math**

well the price 2p for the 2 CDs produces 1.49 sales tax, so .05(2p) = 1.49 Now you can find p.
*January 2, 2015*

**math-algebra HELP!!!!**

do you not have a linear regression tool for finding a line of best fit? Use it, then the answers should be clearer. Just eyeballing the data, we can first sort it: 32 72 34 76 35 75 37 77 37 78 42 81 46 88 Looks to me like I'd expect about 44 chirps at 85°
*January 2, 2015*

**Calculus**

well, you know that critical points occur when h'(x)=0. So, we want 3x^2+b = 0 at x=2. So, b = -12 That means that h(x) = x^3-12x+d h(2) = 8-24+d = -4 So, d = 12, giving us h(x) = x^3-12x+12 The graph is at http://www.wolframalpha.com/input/?i=x^3-12x%2B12+for+x%3D0..3 ...
*January 2, 2015*

Pages: <<Prev | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | **15** | 16 | 17 | 18 | 19 | 20 | 21 | Next>>