Thursday

May 5, 2016
Total # Posts: 40,168

**Parametric Curve**

visit wolframalpha.com and type in your functions, as in (d) below http://www.wolframalpha.com/input/?i=parametric+plot+x%3D%282t+%2B+1%29sint,+y%3D%282t+%2B+1%29cost
*May 4, 2016*

**Parametric Curve**

visit wolframalpha.com and type in your functions, as in (d) below http://www.wolframalpha.com/input/?i=parametric+plot+x%3D%282t+%2B+1%29sint,+y%3D%282t+%2B+1%29cost
*May 4, 2016*

**Parametric Curve**

visit wolframalpha.com and type in your functions, as in (d) below http://www.wolframalpha.com/input/?i=parametric+plot+x%3D%282t+%2B+1%29sint,+y%3D%282t+%2B+1%29cost
*May 4, 2016*

**Math**

The following table shows the rate of water flow (in L/min) through a dam. t (min) 1 6 11 16 21 26 31 V'(t) (L/min) 1 8 2 9 7 5 9 Approximate the total volume of water that passed through the dam from t=1 to t=31 using Simpson's rule, with n=6.
*May 4, 2016*

**Math**

looks good to me
*May 4, 2016*

**math**

7*4*h = 56
*May 4, 2016*

**Math**

looks like 3/5 to me oh, you mean 3/5 each? Then that would of course be 4 * 3/5 = 12/5
*May 4, 2016*

**Math**

Nope. It is 7!, but that's not 2520
*May 4, 2016*

**Math**

well, (3+7)/2 h = 25
*May 4, 2016*

**Algebra**

yes a^x where a is any constant is an exponential function
*May 4, 2016*

**Pre-Algebra**

you mean area, or length? If area, then (16+6w+2w)(48+6w+2w)-(16+6w)(48+6w) = 28w^2 + 128w in^2
*May 4, 2016*

**Algebra 2**

D = |2 3| |3 5| so B is out Replace the 1st column with (5,7) and that gives D.
*May 4, 2016*

**Algebra**

nope: add 10^3 * 10^5 = 10^8 what you have is 10*10*10 * 10*10*10*10*10 you multiply the numeric part 3*10^2 * 2*10^5 = 3*2 * 10^2*10^5 = 6*10^7
*May 4, 2016*

**Math**

all it tells me is that it is a parabola that crosses the x-axis at 4 and -2/5.
*May 4, 2016*

**math**

drama scale? You mean drawn to scale? 2(.005*6 + .005*13 + 6 * 13) = 156.19 m^2 I suspect a typo.
*May 4, 2016*

**Urgent help Ms sue**

i guess so
*May 4, 2016*

**Urgent help Ms sue**

how can the three designs be used to combat truancy in schools?
*May 4, 2016*

**Urgent help Ms sue**

Education researchers believe that a new approach to tackling truancy may help to reduce truancy levels. They wish to carry out a trial to compare the efficacy of the new approach with an existing approach. It is known that some schools have lower truancy rates than others, ...
*May 4, 2016*

**math**

no - it depends on where they started.
*May 4, 2016*

**math**

just change the sign of all the x-coordinates. try graphing and flipping a few points to see why this is.
*May 4, 2016*

**Math**

well, F=ma plug and chug. watch the units. Using clear English would also help...
*May 4, 2016*

**SAT math**

P(t) = 300,000
*May 4, 2016*

**algebra**

If you have x lbs of deluxe and y lbs of economy, then you want to maximize p=7x+5.4y subject to x/2 + y/2 <= 130 2x/3 + y/3 <= 170 now graph the lines and find the vertex with maximum p.
*May 4, 2016*

**huh?**

You want to try that in short clear sentences the way you got it? Don't make us figure out the question as well as the answers...
*May 4, 2016*

**Phy**

is the change linear? If so, then since 2.3 is 3/5 of the way from 2.0 to 2.5, the temperature would be 3/5 of the way from 0 to 100 degrees.
*May 4, 2016*

**Algebra 1**

.30(90-x) + 0(x) = .23(90)
*May 4, 2016*

**math**

Friday: the amounts are n and j Saturday: 2n/3 and j+n/3 Sunday: 2n/3 + (1/3)(j+n/3) and (2/3)(j+n/3) = j/3 + 7n/9 and 2j/3 + 2n/9 so, j/3 + 7n/9 = 96 2j/3 + 2n/9 = 120 Nathan had $54 and Jasper had $162 I'll let you verify the accuracy of the solution.
*May 4, 2016*

**math, functions**

g(x) = f(f) = 1/(1-f) = 1/(1-(1/(1-x)) = 1 - 1/x h(x) = f(g) = 1/(1-g) = 1/(1-(1 - 1/x)) = x But, as you say, watch for places where f is undefined. I'm sure you can figure those out.
*May 4, 2016*

**Algebra 1**

you want to decrease the concentration by 23/30, so that means you have to increase the volume by 30/23. 30/23 x = 90 x = 90 * 23/30 = 69 So, add 21 gallons of water
*May 4, 2016*

**DamotAk mathematecs**

x^2 = 90^2 + 90^2 - 2*90*90*cos(140°)
*May 4, 2016*

**Trig**

amplitude of 3/5: 3/5 cos(x) period of 3pi/2: 3/5 cos (4/3 x) y-intercept of 5: 22/5 + 3/5 cos (4/3 x) http://www.wolframalpha.com/input/?i=22%2F5+%2B+3%2F5+cos+%284%2F3+x%29
*May 3, 2016*

**Algebra**

so, the new tanks will hold (5/4)^3 as much oil, or 23437.5 gallons each
*May 3, 2016*

**Math**

Zoe feeds 6 horses per hour Matt feeds 2 horses per hour. So, together they feed 8 horses per hour, taking 4 hours to feed 32 horses
*May 3, 2016*

**Math**

40+10+25m = 50+15m+10m as given, if the Zumba class is each month, then both Gyms cost exactly the same: $50 in fees and $25 monthly
*May 3, 2016*

**geometry**

∠A = 15+15 = 30 = ∠B ∠C = ∠D = (360-30-30)/2 = 150 so, ∠ACD = 180-150-15 = 15 ∠BCA = 150-15 = 135
*May 3, 2016*

**PLEASE HELP ASAP**

looks good. when you say my answer is a? are you asking what your answer is?
*May 3, 2016*

**math**

since time = distance/speed, 24/(x-4) + 24/(x+4) = 14
*May 3, 2016*

**maths**

what is the coefficient of (x+2)^3 in the cubic taylor polynomial about -2 for the function f(x)= e^x?
*May 3, 2016*

**Geometry (check my work)**

why would you compare volume to surface area? The volumes are scoop: pi/6 * 6^3 = 113.1 cm^3 cone: pi/12 * 5^2 * 9 = 58.90 cm^3 the cone is too small, but because the volumes compare so.
*May 3, 2016*

**Maths Please help**

What is the quadratic Taylor polynomial about 2 for the function f(x)=square root x-1?
*May 3, 2016*

**maths**

surely you have the formula. What's the trouble? Just express it as a polynomial in (x + pi/3)
*May 3, 2016*

**maths**

What is the Linear Taylor polynomial aout -(pi/3) for the function f(x)=sin(x)?
*May 3, 2016*

**Maths ple**

b^8 is the 9th term, so its coefficient is 17C9 = 24310
*May 3, 2016*

**Maths ple**

what is the coefficient of a^9b^8 in the expansion of (a+b)^17
*May 3, 2016*

**Please help**

d=3, so there are 1+(260-2)/3 = 87 terms S87 = 87/2 (2+260) = 11,397
*May 3, 2016*

**Math**

L(L-3)=70 Hmmm. 10*7 = 70
*May 3, 2016*

**algebra PLEASE HELP ASAP**

looks good to me. 1 M in 7 letters.
*May 3, 2016*

**Math**

20 scores, with 5 less than 2.34 5 is 25% of 20, so the 25th %ile or 6 <= 2.34, making it the 30th %ile
*May 3, 2016*

**Algebra**

clearly you have skipped the definitions. arithmetic has terms which differ by the same amount geometric has terms with a common ratio, one to the next. a) has a ratio which changes: A(n) = A(n-1)*n A(n)/A(n-1) = n, which is not constant not GP or AP b)That +8 is a dead ...
*May 3, 2016*

**math**

do you have some kind of calculation to buttress your gut feeling? play with some numbers, at least.
*May 3, 2016*

**math**

original: n/d new: .5n/.75d = (2/3)(n/d) so, it is decreased by 33.3%
*May 3, 2016*

**Math -Trig**

for any x, cot(x) = 1/tan(x) 3pi/4 is in Quadrant II, so draw the triangle. x = -1 y = 1 cot(3pi/4) = x/y = -1/1 = -1 or, consider that cot(pi-x) = -cot(x) since cos(pi-x) = -cos(x) and sin(pi-x) = sin(x) so, cot(3pi/4) = cot(pi - pi/4) = -cot(pi/4)
*May 3, 2016*

**Math - Trig**

12 revolutions per minute 3.5*pi meters per revolution ...
*May 3, 2016*

**math**

Apparently greedy Ashley already had 1/4 of a pizza! anyway, 1 3/4 = 7/4 divide that by 11, as we're just talking about the friends.
*May 3, 2016*

**half-life**

.5mg is 1/8 of 4 mg 1/8 = (1/2)^3 so, that's 3 half-lives
*May 3, 2016*

**math**

60/36 ft * 12in/ft
*May 3, 2016*

**maths**

200 sin40
*May 3, 2016*

**Math**

1/6 of the time for each number.
*May 3, 2016*

**math**

11!/(2!2!2!2!) = 2,494,800
*May 3, 2016*

**Calculus**

see a nice calculator here to check your work: http://www.emathhelp.net/calculators/calculus-2/simpsons-rule-calculator/
*May 3, 2016*

**math**

(60 * 0.80 - 10) * 1.55 = $58.90
*May 3, 2016*

**math**

a = b + 0.50b = 1.5 b b = a/1.5 = 2/3 a so, b is 1/3 less than a, or 33.3% less
*May 3, 2016*

**math**

increasing by N% means the new value is 1+N/100 as much as the old value. So, we have new = old*(1+1)(1+1.5) = 5.00 * old so, old = new/5 or 20%
*May 3, 2016*

**math**

x * 1.25 = 2 x = 1.6 so, the first increase was 60%
*May 3, 2016*

**urgent math**

#1. 7^(9-3) = 7^6 NOT 7^(9/3) = 7^3 subtract exponents when dividing numbers. What you have is 7*7*7*7*7*7*7*7*7 ------------------------ 7*7*7 only three of the 7's cancel #2 z^8/z^12 = 1/z^4 = z^-4 So, D, not C #3 ok #4 not sure what ...
*May 3, 2016*

**Math**

two adjoining trapezoids produce a figure with six sides. You only give four lengths. You will need to use the sides and the Pythagorean Theorem to determine the heights of the trapezoids. Then it's easy, since you know the formula for the area of a trapezoid, given its ...
*May 3, 2016*

**Algebra**

#10. since 1=√1, you must have -2v-3 = 1 #11. √(n+5)= √(5n-11) n+5 = 5n-11 n = 4 check: √9 = √9 #12. well, geez, just check them! √(12-(-4)) = √(12+4) = √16 = 4 Since this is not equal to -4, that value is extraneous. √(12-...
*May 3, 2016*

**math**

independent means they can both happen, and do not affect each other. Like two consecutive rolls of a die. Rolling a 3 and then a 6 are independent, and can both happen. Mutually exclusive events cannot both happen, such as flipping a coin and getting both a head and a tail. ...
*May 3, 2016*

**Science**

well, time = distance/speed, so just crank it out.
*May 3, 2016*

**Math**

(2 – 9c)(–8) 2(-8)+(-9c)(-8) -16 + 72c
*May 3, 2016*

**Geometry/Trig**

since the acute angles are 45°, the two legs are both 16 (a fact you left out) so, the hypotenuse is √(16^2 + 16^2) = 16√2
*May 3, 2016*

**chemistry**

moles KOH = .0175 * .553 = .00968 so, you need that many moles of HBr, making the molarity M = .00968/.025 = 0.387
*May 3, 2016*

**Math**

x - x/3 + 25 = 115
*May 3, 2016*

**math 1324**

x+y+z = 2000000 .07x + .085y + .095z = 169750 y = 4z see the matrix solution at http://www.wolframalpha.com/input/?i={{1,1,1},{.07,.085,.095},{0,1,-4}}*{{x},{y},{z}}+%3D+{{2000000},{169750},{0}} {{1,1,1},{.07,.085,.095},{0,1,-4}}*{{x},{y},{z}} = {{2000000},{169750},{0}}
*May 3, 2016*

**Analytic Geometry**

cot2θ = 0 so θ=45° Then just do the rotation matrix stuff to find the equation in the new coordinates.
*May 3, 2016*

**math**

won = 15+3*lost won + lost = 123 lost = 27 won = 96
*May 3, 2016*

**math**

3/200 = 1.5/100 = 1.5%
*May 3, 2016*

**Math**

tanx/sinx = 1/cosx cosx=0 at odd multiples of pi/2. So, that is where you have asymptotes. cosx changes sign at those points, so also does your graph.
*May 3, 2016*

**math**

depends on the area of the base. Divide the volume by the area to get the height.
*May 3, 2016*

**math - eh?**

huh?
*May 3, 2016*

**math - Correction.**

that is an obtuse angle. I'd say 0° < d < 90°
*May 2, 2016*

**Maths**

The three numbers will therefore be close to 21.98. So, I'd say they'd be 21,22,23 whose product is 10626
*May 2, 2016*

**math**

480ft/30s * 60s/min = 960 ft/min
*May 2, 2016*

**math**

not so. you have found d/dt (dy/dx), but you want d/dx (dy/dx) = d/dt(dy/dx) / dx/dt = -1/(1+t)^2 / e^t = -1/((1+t)^2 e^t)
*May 2, 2016*

**TRIGONOMETRY2**

can't use google? 1st hit led to http://www.cut-the-knot.org/proofs/2Colors2Points.shtml#solution
*May 2, 2016*

**TRIGONOMETRY**

√(x+b)-√(x-a) >= √(x+a)-√(x-b) since x>=a>=b, we have x+b >= 2b x-a >= 0 x+a >= 2a >= 2b x-b >= x-a see what you can do with that
*May 2, 2016*

**Math**

the ratios are: length: 11/33 = 1/3 width: 7/28 = 1/4 so, not similar
*May 2, 2016*

**math**

not quite. log(x^2) = 2logx 150 = 3*100/2, so log 150 = log3 + 2log10 - log2 75 = 3*(10/2)^2, so log75 = log3 + 2log10 - 2log2 or, since 75 = 150/2 log75 = log150-log2 as above
*May 2, 2016*

**Probability**

1/15000 (1000 + 2*300 + 20*10) = 3/25
*May 2, 2016*

**Math**

there is no limit. There must be some other considerations.
*May 2, 2016*

**Geometry**

well, just check. a sphere with diameter d has volume π/6 d^3 3*(π/6)(5^3) = 375π/6 (π/6)*8^3 = 512π/6 π/12 * 10^3 = 500π/6
*May 2, 2016*

**calculus**

94 ∑ k k=3 assuming you meant ... 144, 12 ∑ k^2 k=3
*May 2, 2016*

**Algebra**

y=5x
*May 2, 2016*

**pre-cal**

as they said, the total area is xy as for the print area, that is (x-2)(y-3) = 26
*May 2, 2016*

**calculus**

maximize p=x(30-x)-100-6x subject to x >= 10 x <= 20 the profit is revenue-cost, so p(x) = x(30-(x-10)) - 100 - 6x = -x^2+34x-100 dp/dx = 34-2x dp/dx=0 at x=17
*May 2, 2016*

**calculus**

this is just the chain rule in reverse. G'(x) = cos(x^2) (2x)
*May 2, 2016*

**calculus**

change all the t's to x^2, then multiply by (x^2)' G(x) = cos(x^2)(2x)
*May 2, 2016*

**math**

it is a function whose graph is s straight line.
*May 2, 2016*

**calculus**

Sketch the region. It has vertices at (0,0), (2,0), (4,2) You can get the area by using vertical or horizontal strips. Using vertical strips, they all lie below the curve √x, but the lower boundary changes from y=0 to y=x-2 at x=2. So, the area is ∫[0,2] √x ...
*May 2, 2016*

**math**

as usual, v = Bh = 20*10 = 200 cm^3 note that the area of the base must be in cm^2, not just cm.
*May 2, 2016*