Thursday
December 8, 2016

Posts by steve

Total # Posts: 46,999

Math
Not quite. ?(75p^3q^2) = 5?3 pq?p ?(p^5q^4) = p^2q^2 ?p divide and you end up with (5?3)/(pq) Hmm. I guess you could have meant 5?(3/(p^2q^2)) but that simplifies to my result above
December 6, 2016

Cal 3
critical points are where they are both zero. So, you need x^3+y^3-15x^2-6xy+18y^2+39x+138y 3x^2-30x-6y+39 = 0 3y^2-6x+36y+138 = 0 http://www.wolframalpha.com/input/?i=solve+3x%5E2-30x-6y%2B39+%3D+0,+3y%5E2-6x%2B36y%2B138+%3D+0 http://www.wolframalpha.com/input/?i=minima+x%5E3...
December 6, 2016

Algebra II
real: 4,2,0 Using Descartes' Rule of Signs, positive: 2 max negative: 2 max complex: 4,2,0 how come (a),(b),(c) are all the same?
December 6, 2016

Trigonometry
cot(x) has period pi cot(x/3) has period 3pi Now add in the rest.
December 6, 2016

Applied calculus
pi, not pie or pai or ... try typing your functions in here. http://www.wolframalpha.com/input/?i=plot+x%3D2cos(2t),+y%3D2sin(3t),+0%3C%3Dt%3C%3D2pi rather than expressing them as vector components, use parametric equations.
December 6, 2016

Algebra
keep track of the amount of antifreeze in each part, and the whole: .25x + .60*4 = .45(x+4)
December 6, 2016

CALC
google is your friend. Many of these problems have been solved before, or ones like them. www.math.umn.edu/~emanlove/2263sum11/HW%2034.pdf
December 6, 2016

precalculus
well, geez -- just look at the equations. Surely you can notice the +/- signs, axis lengths, etc.
December 6, 2016

Calc
dy/du = sec^2u du/dv = 1 + 1/v^2 dv/dx = 1/x dy/dx = dy/du * du/dv * dv/dx now just crank it out. It's just algebra from here.
December 6, 2016

math
is (2,1) supposed to end up at (-1,4)? If so, why the intermediate point? The final translation is just (x,y) -> (x-3,y+3)
December 6, 2016

Science. Answer Check
false. In a series circuit, one failure causes the whole chain to stop. Parallel means that the current flows through each light "in parallel" with the others -- the lights each get their own current. Better look at a circuit diagram again to refresh your memory.
December 6, 2016

math
Hmmm. The problem says 9 people. How do you justify your answer?
December 6, 2016

Algebra
6200 * 1.08^t = 8750 * 1.06^t (1.08/1.06)^t = 8750/6200 ...
December 6, 2016

elimination
rearrange things to a standard format: x - 2y = -7 8x + 5y = 7 multiply #1 by 8: 8x - 16y = -56 8x + 5y = 7 Now just subtract, and the x's are eliminated...
December 6, 2016

math
Nope. -5(8) = -40 Now subtract 4 Your answer is -4 -5(w-8)
December 6, 2016

math
a=7 d=3 ...
December 6, 2016

Math
If the distance is x, then we have for the area a = 15*4 = 8x
December 6, 2016

Maths
looks like 4.5 for depth, -4.5 for height
December 6, 2016

math
2?rh = 1760 ?r^2h = 12320 square the area equation, and now you have 4?^2 r^2 h^2 = 1760^2 ?r^2 h = 12320 Divide and you have 4?h = 1760^2/12320 ...
December 6, 2016

Math
Your equation just satisfies y varies directly as x. What about the rest? y = ax + b/x + c Now use the points to get 3 equations in a,b,c and solve them.
December 6, 2016

Calc
dy/dx = dy/dt / dx/dt = (3/(2?(3t+1))) / (3t^2-1) at x=1, that is (3/(2*2))/(2) = 3/8
December 6, 2016

Calc
plug in lnx for x and then use the chain rule. f(lnx) = 6(lnx)^3 - 4lnx
December 6, 2016

Calculus
The question is incomplete: smallest n for what? You can easily verify that y^(2) = -y y^(4) = y and the odd orders are plus/minus cosine.
December 6, 2016

Maths
see related questions below
December 6, 2016

Math
If the numerator is even and differs by 3 from the denominator, then the denominator is odd. (Thus, the prime 2 is ruled out.) At that point, saying that their product is even is redundant. odd primes are 3,5,7,11,13,... So, the fraction could be 2/5, 4/7, 14/11, ...
December 6, 2016

G.p.
again? ar^6 = 1/9 ar = 27 divide, and you have r^5 = 1/3^5 r = 1/3 So, a=81
December 6, 2016

maths
2*5 = 10 so its fractions terminate. Try using 3 and see what happens.
December 6, 2016

Meth
fix the typo. Then maybe we can pick an answer.
December 6, 2016

harmonic progression
since the reciprocals are in AP, yes, it is an HP.
December 6, 2016

Algebra
well just plug in t=6 into your somewhat awkward formula.
December 6, 2016

G.p.
is that 2^(2-b) or 2^2 - b?
December 6, 2016

math
x + x+2 = x+4 + 16
December 6, 2016

g.p.
ar^3/ar^11 = 1/r^8 = 1/2^8 so, r = 2 I expect you can take it from there...
December 6, 2016

Calculus
I'd say no. It's just an exponential function. No way any logs can creep in there.
December 6, 2016

Calculus
well, geez - did you try it to check? f = e^(1-x) = e*e^-x f' = e*(-1)e^-x = -f
December 6, 2016

Calculus
Just using the product, quotient, and chain rules, I'd say (u'v + uv')(w) - uvw' ---------------------------       w^2
December 6, 2016

Calculus
y = x + 4/x has a max at x = -2
December 5, 2016

Calc
v = x(6x)*y y = V/(6x^2) A = x*6x + 2xy + 2*6xy = 6x^2 + 14xy = 6x^2 + 14x(V/6x^2) = 6x^2 + 7V/(3x) Now just find where dA/dx = 0.
December 5, 2016

Alegbra
you have basically a = bR^3 R^3 = a/b = 15000/(4pi/3) = 45000/4pi = 11250/pi R = ?(11250/pi)
December 5, 2016

Pre Calculus
just solve for t when h(t) = 0.
December 5, 2016

Math
A better question might be how did you get yours? Did you draw a diagram? since sin(30) = 1/2, the pole is 15/2 meters tall. A 45-45-90 triangle has equal legs, so base of the 2nd wire is 15/2 meters from the pole. I'll leave the rest to you. The Pythagorean Theorem should...
December 5, 2016

Math
That's not what I get. I get (15/2)(?3-1) How did you get your answer (which is not exact, by the way)?
December 5, 2016

Algebra
the maximum profit is at the vertex of the parabola. As you know, the vertex of the parabola ax^2+bx+c is at x = -b/2a y = (b^2-4ac)/4a So, for -10x^2+100x-210 the vertex is at (5,40) Since x=5, the price is 10-x = 5 as well.
December 5, 2016

math
If their numbers are x,y,z, then we know x/y = 2/7 x/z = 2/3 z = y-8 x+y+z = 24
December 5, 2016

Science
Recall that F = ma Now just use your numbers.
December 5, 2016

Algebra
Recall that the parabola x^2 = 4py has its vertex at (0,0) and its directrix at y = -p.
December 5, 2016

Algebra
If we set the vertex at (0,0) then the curve goes through (30,30) y = 1/30 x^2 x^2 = 30y Since the parabola x^2 = 4py has its focus at y=p, 4p=30 and the mic should be 15/2 inches up from the vertex.
December 5, 2016

maths
well, it lost 12%, so it retains 88% of its initial value. So, ...
December 5, 2016

Calculus
f(lnx) = 6(lnx)^3 - 4lnx Now you can use the chain rule.
December 5, 2016

maths
google is your friend. You could have solved this problem in one minute: https://www.algebra.com/algebra/homework/Circles/Circles.faq.question.308572.html
December 5, 2016

Math
32 hr * 6 lawns/8hr = 24 lawns
December 5, 2016

Math
1/10 + 1/B = 1/6
December 5, 2016

Math
check to see how much salt is coming in and going out. Since pure water contains no salt, and the 5 gallons leaving contain 5/100 of the salt present, we have ds/dt = 5/100 * 0 - 5/100 s ds/dt = -1/20 s ds/s = -1/20 dt s = c*e^(-t/20) Since s(0) = 10, s = 10*e^-(t/20) so, let...
December 5, 2016

Math
see the related questions below. They should help you set up and solve your differential equation. If you get stuck, come back with what you have done so far.
December 5, 2016

Calculus
you are correct: http://www.wolframalpha.com/input/?i=plot+y%3Dx%5E3%2B1%2F4,+y%3D3x%2F4,+-1%3C%3Dx%3C%3D1
December 5, 2016

Math
x^3+2y^3 = 5xy 3x^2 + 6y^2 y' = 5y + 5xy' y'(6y^2-5x) = 5y-3x^2 y' = (5y-3x^2)/(6y^2-5x) y" = [(5y'-6x)(6y^2-5x)-(5y-3x^2)(12yy'-5)]/(6y^2-5x)^2 2xy(54x^3-270xy+108y^3+125) --------------------------------------       ...
December 5, 2016

parametrics
Your parametric equations are right. The second quadrant is pi/2 <= t <= pi
December 5, 2016

Math
At height h, h/4 = tan? 1/4 dh/dt = sec^2? d?/dt So, plug in your numbers and find dh/dt
December 5, 2016

Geometry
Assuming the three points lie on a single line, then since the slope is constant, (5-2)/(4-1) = (2-0)/(1-x) x = -1 Note that x changes by the same amount as y between points. Since y changed by -2, from 2 to 0, x changed by -2, from 1 to -1.
December 5, 2016

precalculus
x^2/a^2 + y^2/b^2 = 1 The semi-axis lengths are a and b. Naturally, the larger is the major. If it's a, the ellipse lies horizontally. If it's b, the ellipse stands up, because the major axis is vertical.
December 5, 2016

geometry
since PB is the bisector, the other two angles are equal. x+2 = 2x-6 solve for x, and then you can find your angle.
December 5, 2016

Calc
f(x)=2sinx-sin2x f(7pi) = 0 f(8pi) = 0 f(x) is continuous. So, it satisfies the MVT. In fact, it satisfies Rolle's Theorem. (f(8pi)-f(7pi))/(8pi-7pi) = 0 f'(x) = 2cosx - 2cos(2x) = 2cosx - 2(2cos^2x-1) = -4cos^2x + 2cosx + 2 = -2(2cos^2x - cosx - 1) = -2(2cosx+1)(cosx-...
December 5, 2016

Calc
see your other post
December 5, 2016

precalculus
replace y by (y-k) and x by (x-h) Better review your text where it talks about translation of functions.
December 5, 2016

precalculus
you know what y=ax^2 is, right? Now shift it by (h,k)
December 5, 2016

Math
You can always multiply by 1 without changing things. A conversion factor is just a way of writing 1 so that units cancel as desired. Suppose you want to convert lbs to kg. You know that 2.2lb = 1kg So, 2.2lb/1kg = 1 1kg/2.2lb = 1 So, if you want to convert kg to lbs, you can ...
December 5, 2016

Math
P(1st=0) = 1/6 P(2nd=0) = 1/6 P(either) = 1/3
December 5, 2016

Math
The same as the probability that either of them is zero.
December 5, 2016

precalculus
(a) and (b) are equivalent, since you can write them as (y-k) = a(x-h)^2 (y-k) = 4p(x-h)^2 You have (b) and (c) right. I thought we already went over this...
December 5, 2016

Mathematics
No, you must check. You already have the alleged answers!
December 5, 2016

Maths
you are correct, but it seems a bit convoluted. Still, if it helps you sort out the quantities, good job.
December 5, 2016

precalculus
I don't see any questions. Just statements of the properties. If you understant (x-h)^2 = 4p(y-k) then I don't see what the problem is with (y-k)^2 = 4p(x-k) Go to wolframalpha.com and type in some functions and see what happens. For example, http://www.wolframalpha....
December 5, 2016

Calculus 1
x dx/dt + y dy/dt = 0 Now just plug in your numbers.
December 5, 2016

Math
the unit price per egg is 48/30. Add 15% profit and multiply by 100: (48/30)*1.15*100 = Rs 184
December 5, 2016

Calc
correct. Having trouble visualizing that, where h tries to change from concave down to up at x = -1, but fails, and stays concave down? h(x) = x^6/30 + 3x^5/20 + x^4/12 - x^3/2 - x^2 It's a strange bird. You can see it straightening out, then staying concave down until x=1...
December 5, 2016

Calc
As you can see, g'(1)=0 twice. So, g' is negative on both sides. That means the function is falling, comes to a momentary stop, and then keeps on falling. (Think of y=x^3, y'=3x^2. y'=0, but is rising on both sides.) g(1) is neither a max nor a min. Since g'...
December 5, 2016

Maths
a+4d = 3(a+d) a+11d = 2(a+5d)+1 Solve for a and d, then T16 = a+15d
December 5, 2016

algebra, mathematics
x + y = 33 y - 2x = 15
December 5, 2016

Silmultaneous Equations
I'll just use x and y, giving ?(5/8-(?5/8))x+cos(43°)y = 0 0.58778x + 0.73135y = 0 1/4(1+?5)x+sin(43°)y-2g=0 0.80902x + 0.68200y = 19.6 Now just solve by your favorite method (I suggest substitution).
December 5, 2016

Silmultaneous Equations
what do the LH and RH mean?
December 5, 2016

Math
no, it's not
December 5, 2016

math115
Your equation shows him just getting 1/2 time for extra hours. For time and a half, you need P(t) = 880 + 22*1.5(t-40) = 880 + 33(t-40)
December 5, 2016

Math
42
December 5, 2016

math
what, no possible ideas for this? Let x be the number. Then four times a number is 4x now work on the rest of the clues. Just put them into math symbols.
December 5, 2016

fundamental programming
x=5 while (x?0) read x
December 5, 2016

Math grade 10
the slope of AB is 1/4 So, you want a line with slope -4 that contains C(1,4). Use the point-slope form, and you have y-4 = -4(x-1)
December 5, 2016

Math - Coordinate Geometry
you have a slope (4) and an intercept (-3), so try the slope-intercept form: y = 4x-3
December 5, 2016

math
.25x + .60(90-x) = .53*90
December 4, 2016

Math
So, I guess you did not read the web page I suggested ... r = ed/(1+e sin?) r=4/(-2-6sin?) r = -2/(1+3sin?) so, e=3 and d=2/3 in x-y coordinates, that is (y-3/4)^2 - x^2/8 = 1/16 http://www.wolframalpha.com/input/?i=hyperbola+(y-3%2F4)%5E2+-+x%5E2%2F8+%3D+1%2F16 You can see ...
December 4, 2016

Algebra
one way is just plain substitution. You know that y = 5x-3, so use that in the other equation: y = -3x+5 5x-3 = -3x+5 8x = 8 x = 1 Now, y = 5x-3 = 5-3 = 2 substituting for x will also work, but then you have fractions to work with, since x = (y+3)/5 or (5-y)/3
December 4, 2016

Algebra
The + on the left means it's a circle or ellipse. The differing coefficients for x^2 and y^2 means it's an ellipse. In standard form, that is just x^2/25 + y^2/9 = 1
December 4, 2016

Math
You say Suppose m?438° what does that mean? Hmm. Maybe you mean m?4 = 38° Not sure what the figure looks like, but corresponding angles are congruent. Check for adjacent angles or alternate/vertical angles. It's kind of hard to answer a question about a diagram ...
December 4, 2016

PreCalc
every 10s the amount drops by 1/2, so m(t) = 5 * 2^(-t/10)
December 4, 2016

PreCalc
clearly, n(t) = 1500*(12000/1500)^t = 1500*8^t = 1500 e^(2.07944t)
December 4, 2016

Math
suppose I said 8 = r/4 How would you do that? Multiply by the denominator, right? So, r = Td Now divide by T to get d all alone: d = r/T
December 4, 2016

Math
We are talking about 7*24+1 = 169 hours. So, the clock loses 84.5 minutes in that time. ...
December 4, 2016

Math
depends on the coins.
December 4, 2016

Math grade 10
Just verify that they intersect at (3,3)
December 4, 2016

Maths
sorry. that's ?x-2?
December 4, 2016

Maths
y = 0.50 for x <= 2 0.50 + 0.10(x-2) for x > 2 technically, it is a step function, so y = 0.50 + 0.10⌈x-1⌉ for x > 2
December 4, 2016

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