Sunday

February 7, 2016
Total # Posts: 37,460

**anty alice**

type you equation in at wolframalpha.com
*February 4, 2016*

**math**

Draw a diagram. The slant height is s = 42/cos30°
*February 4, 2016*

**maths**

check the intercepts. when x=0, y=b when y=0, x=a so, you have a right triangle with legs a and b, so its area is ab/2
*February 4, 2016*

**Calculus**

If the angle is x, then you have a trapezoid with lower base 4", and upper base 4+2*4cosx, and height 4sinx. So, the area of the cross-section is a = (4 + (4+8cosx))/2 * (4sinx) = 16 sinx (1+cosx) da/dx = 16(2cos^2(x)+cos(x)-1) = 16(2cosx-1)(cosx+1) da/dx=0 when cosx = 1/...
*February 4, 2016*

**circumference...math**

recall that the circumference of a circle of diameter d is C = πd
*February 4, 2016*

**Math**

vertical angles are equal, so 7x+7=112 x=15 you are correct.
*February 4, 2016*

**math**

solve for t with e^(.10*t) = 2
*February 4, 2016*

**math**

the small gear turns 4 times as fast as the large one.
*February 3, 2016*

**Math**

looks ok to me.
*February 3, 2016*

**maths**

well, here's the graph: http://www.wolframalpha.com/input/?i=%282^x%29%28cot+x%29%2Fx^1%2F2 did you have some question about it?
*February 3, 2016*

**MATH**

well, a = 8 r = 3/4 Tn = 8 * (3/4)^(n-1)
*February 3, 2016*

**Calculus**

what is the height of the tank? You need to know how far above the top of the oil is the spout, and how deep is the oil. Anyway, assuming the oil has a depth of d meters, and the spout is h meters above the top of the oil, then consider the oil as a stack of thin slices of ...
*February 3, 2016*

**Calculus**

a = dv/dt, so v(t) = 2t^3 = 2*6^3
*February 3, 2016*

**Calculus**

all look ok to me. good work.
*February 3, 2016*

**calculus 1**

clearly the limit is (8+1)/(6-4) = 9/2 Not sure what your definition 2 is, but if you need to find δ such that |f(x+δ)-9/2| < 0.5 then that means |(4(2+δ)+1)/(3(2+δ)-4)-9/2| < 0.5 Work your way through that and you will find that δ < 0.125 So...
*February 3, 2016*

**Math **

(a) stretch by 2 and shift up 3 (b) shift left 1 and down 3 (c) shrink by 2 and reflect in x-axis (d) shift left 1, reflect in y-axis, reflect in x-axis, shift up 3. Just plug in your numbers to find the image of the point.
*February 3, 2016*

**Geometry**

22+16-32 = 6 So, there are 6 juniors who do both. P(both) = 6/50 = 3/25
*February 3, 2016*

**Math**

assuming you have a hemisphere atop a cylinder, they both have the same radius. So, just plug your numbers into the usual volume formulas.
*February 3, 2016*

**Math**

clearly y is discontinuous at x=0, since lim(x->0-) = 3 lim(x->0+) = 1 y'=-2x for x<0 y'=2x for x>0 y" = -2 for x<0 y" = +2 for x>0 so, y is increasing everywhere, since y'>0 everywhere it is defined. y is concave down for x<0 y is...
*February 3, 2016*

**Writing equations to represent situations**

x = 17 xy = 680 2(x+y) = ?
*February 3, 2016*

**Math**

1: probably a trapezoid 2: Must mean that there are two such congruent sides, not that all pairs are congruent. Might be a trapezoid or a kite. 3: could be a rectangle or trapezoid. Diagonals of a rhombus are not equal. 4: general quadrilateral. Try drawing one 5: kite Try ...
*February 3, 2016*

**Math**

well, there are 57/y bananas That means there must be only 57/y apples, so the result will be 57/y oranges, each having mass x+y so, the mass of oranges will be 57(x+y)/y = 57(1+x/y) grams
*February 3, 2016*

**Math**

as always, swap variables and solve for y: 3x+5y=18 5y = 18-3x y = (18-3x)/5 Did the other one in your previous post (see related questions below)
*February 3, 2016*

**Math**

I think you are missing something. Each added triangle has a smaller area and a smaller perimeter. I think I am missing something, too. If all the triangles are inscribed into the same area, the total area is unchanged, right? By "the perimeter" do you mean the sum ...
*February 3, 2016*

**math**

y = 144+(115.2-144)/(14) x = 144-2.057x Now just plug in values for x.
*February 3, 2016*

**Algebra**

(6x^-2)^2 = 36 x^-4 (1/2 x)^4 = 1/16 x^4 multiply and you get 36/36 = 9/4 = 2.25 If you want us to analyze your work, you need to show it!
*February 3, 2016*

**algebra**

if there are all positive exponents, then it is a polynomial. Terms are separated by +/- signs, so just count the terms to determine the type. Add the exponents in each term; the highest sum is the degree of the polynomial.
*February 3, 2016*

**science/maths**

divide those time values by 60, since they are in minutes, not hours.
*February 3, 2016*

**Algebra**

If the slow plane's speed is x mi/hr, then since distance=speed*time, 4x + 4(x+65) = 2660
*February 3, 2016*

**Algebra**

f◦g = f(g) = 3/(g-3) = 3/((2/x)-3) = 3/((2-3x)/x) = (3x)/(2-3x) It looks like the domain of f◦g is all reals except x=2/3, but we also have to exclude x=0, since g is not defined there.
*February 3, 2016*

**math**

it is just the product of the two primes, since there are no common factors.
*February 3, 2016*

**maths**

review the definition of cot(x). Draw a diagram and you can see that h*cot45 - h*cot60 = 100
*February 3, 2016*

**math**

Take a look at this site to see a very similar problem: https://www.quora.com/If-2f-x-3f-left-frac-1-x-right-+-x-2-then-f-2
*February 3, 2016*

**Algebra**

y(t) = y(x(t)) = ln(2*4e^(t/2.5)) = ln(8) + ln(e^(t/2.5)) = ln8 + t/2.5 ≈ 0.4t + 2.08
*February 3, 2016*

**Math**

what you have is an ellipse with semi-axes of 30 and 20 ft, with the long axis horizontal. So, if the center is placed at (0,0) the equation is x^2/30^2 + y^2/20^2 = 1 So, the upper arch is y = 4/9 √(900-x^2) Now just plug in your various values for x to find the height y.
*February 3, 2016*

**Math**

4z-6u
*February 3, 2016*

**math**

1 degree of latitude is approximately 111 km. So, 500km south takes you to 50-500/111 = 4.5°N Naturally, the longitude has not changed.
*February 3, 2016*

**math**

3(m-5)=6m-60 3m-15 = 6m-60 3m=45 m=15 check: 3*(15-5) = 30 = 6*15-60
*February 3, 2016*

**Michael**

probably infinitely many, but the smallest is 1729 = 1^3 + 12^3 = 9^3 + 10^3 as G.H. Hardy learned from Ramanujan.
*February 3, 2016*

**maths**

Hint - think of a 5-12-13 right triangle.
*February 3, 2016*

**singaporean math ratio**

3/7 spent leaves 4/7 1/4 of 4/7 is 1/7, so 3/7 left 3/7 x = 120
*February 3, 2016*

**math**

clearly, that would be 20/50
*February 3, 2016*

**math**

Nope. 30 are boys.
*February 3, 2016*

**geometry**

This is discussed here: https://en.wikipedia.org/wiki/Semiperimeter
*February 3, 2016*

**Numerical Analysis**

well, I don't know what a has to do with x, but pull out your calculator, or use one of the many online calculators, and you can easily learn that tan(1.7) = -7.7 That would have been a lot faster than posting a question like that and having to wait for an answer.
*February 3, 2016*

**Math**

(1/2)(h-2)(h) = 60 Now just solve for h
*February 3, 2016*

**Math**

200+49*2
*February 3, 2016*

**Science**

well, the water was 480 g, so that's 480mL.
*February 3, 2016*

**ACT Prep**

points so far: 72+94+85+83+97 = 431 points needed: 6*88 = 528 Points needed on 6th exam: 528-431 = 97
*February 3, 2016*

**math**

width=w length=2w-8 2(w + 2w-8) = 194
*February 2, 2016*

**Math (precalculus)**

Let the rectangle have width x and height y=33-3x^2 clearly the area is a = xy = x(33-x^2)
*February 2, 2016*

**math**

so, list them all: 1,1 1,2 ... 5,4 5,5 Now -- how many of them have matching spins?
*February 2, 2016*

**Geometry**

that would be (-3,1) + (11+3,9-1)/4 = (-3,1)+(7/2,2) = (1/2,3)
*February 2, 2016*

**Math**

looks good.
*February 2, 2016*

**Math Need Immediate Help????**

how can f(x) include y? h = -4.9(t+3)^2+45.8 h^-1 = √((45.8-t)/4.9)-3
*February 2, 2016*

**differential equations**

what's the trouble? Expand the right side and you have dS/dt = k/MN (-S^3 + (M+N)S^2 - MNS) That's just a polynomial, which you can easily integrate to find S(t)
*February 2, 2016*

**Calculus(PLZ HELP)**

just check out the volume of a spherical cap: http://mathworld.wolfram.com/SphericalCap.html
*February 2, 2016*

**precal**

arctan(3/4) ≈ 37° P is in QIV, so θ = -37° or θ = 360-37 = 323°
*February 2, 2016*

**Math/Algebra**

since time = distance/speed, d/36 + d/48 = 7/2 4d/144 + 3d/144 = 504/144 7d = 504 d = 72 mi
*February 2, 2016*

**math (factorising by grouping )**

skill comes from experience. Just look for common factors. 2ax-6bx+ay-3by You have a 2and a 6, and a 1 and a 3. So, 2x(a-3b)+y(a-3b) (2x+y)(a-3b) Now you try the others.
*February 2, 2016*

**Calc II**

best to use discs of thickness dx. So, v = ∫πr^2 dx where r = 6-y. So, v = ∫[-π/2,5π/2] π(6-(3sinx+3))^2 dx = 81π^2/2
*February 2, 2016*

**Pre-Calc**

Unless they say something, I'd assume QI. In that case, sinθ=5/13 and cosθ=12/13 sinx=3/5 and cosx=4/5 cos (θ+x) = (12/13)(4/5)-(5/13)(3/5) = 33/65 Usually they specify a quadrant if they want to make you determine the sign of the quantities involved.
*February 2, 2016*

**Math**

no formula -- just write down the facts: If pants cost p and shirts cost s, then 3s+2p = 85.50 3s+4p = 123.00 You can now solve for s and p.
*February 2, 2016*

**MATHS**

NOTE THAT Y=11-3X NOW USE THAT IN THE 2ND EQUATION!! 2X-(11-3X) = 4 NOW YOU CAN FIND X, AND THEN Y!! CAN YOU HEAR ME? AM I SHOUTING LOUD ENOUGH???!!
*February 2, 2016*

**Pre-Calc Answer Check**

right on both.
*February 2, 2016*

**Language**

Looks like A or B to me. Two enemies are mentioned, but the eight mentions of quickness and the final friendly offering make me prefer A.
*February 2, 2016*

**Math**

try the addition formulas: 3 cos (ωt + 2) = 3(cosωt cos2 - sinωt sin2) 4 sin(ωt+1) = 4(sinωtcos1 + cosωtsin1) adding them up you get 3cosωtcos2+4cosωtsin1 + 4sinωtcos1 - 3sinωtcos2 Now, according to wolframalpha.com, that gives...
*February 2, 2016*

**Math help please**

9:7
*February 2, 2016*

**algebra**

x+y=5 2x+y=2 Now just solve for x and y
*February 2, 2016*

**eglish**

at least the sentence is correctly written.
*February 2, 2016*

**Math**

#1 ok #2 not quite #3 nope. See all those 9's?
*February 2, 2016*

**SO HARD! MATH**

First, decide whether you are going to stack them on their faces, or on their edges.
*February 2, 2016*

**algebra**

2(a-3) = b+3 a+5 = 2(b-5) A has $11, B has $13
*February 2, 2016*

**Math Help**

No diagram, but probably A, if the two form a straight line.
*February 2, 2016*

**chemistry**

write the balanced equation, then compare ratio of the number of moles of each.
*February 2, 2016*

**algebra**

If the woman is w, and the son is s, then we know w-7 = 4(s-7) w+7 = 2(s+7) woman is 35, son is 14
*February 2, 2016*

**math**

doesn't look like one to me. It's an equation.
*February 2, 2016*

**mathematics extension**

not sure. What was the question? distance from start? bearing from start to finish? Name of pilot?
*February 2, 2016*

**Math**

well, the slope is undefined; the line is vertical. So, the line is x=5 The line y=11 has zero slope. So, the line through (2,-5) is y = -5
*February 2, 2016*

**Maths**

y = x(x+4) The roots are at 0 and -4, so the vertex is at -2. see http://www.wolframalpha.com/input/?i=x^2+%2B+4x
*February 2, 2016*

**math-Polya**

not sure about Polya, but the maximum-area quadrilateral is a square. as for the circle, since c = 2πr and A = πr^2, A = c^2/(4π)
*February 2, 2016*

**Math**

The total points are not 13, but 35+10 = 45. So, using x,y,z for the scoring plays in the same order as described above, 6x+y+3z = 45 x = y x = 6z You certainly don't need elimination for this, since the substitutions are so easy.
*February 2, 2016*

**algebra**

since v = Bh, you have 264 = 48h ...
*February 1, 2016*

**Calculus**

First off, the equation should be (f(x+h)-f(x-h))/(2h) if f(x) = a(x-b)^2+c, then f(x+h) = a(x-b+h)^2+c f(x-h) = a(x-b-h)^2+c f(x+h)-f(x-h) = a((x-b +h)^2 - (a-b -h)^2 = 4ah(x-b) divide that by 2h and you have 2a(x-b) Now, f'(x) = 2a(x-b) ta-daa
*February 1, 2016*

**Precal**

enter your coefficients here: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*February 1, 2016*

**math**

well, if you got 100% on all your tests, that would account for 70% of your grade. So, you'd then need at least 33.3% on the homework. But, if you scored 100% on all the homework, that would account for 30% of your grade, so you'd need 71.43% on the tests. So, the ...
*February 1, 2016*

**More math**

all correct. good work.
*February 1, 2016*

**Math**

if there are c chickens, then there are 40-c cows. So, adding up the legs, 2c + 4(40-c) = 100
*February 1, 2016*

**Do I have enough time**

Don't forget that you will have to spend a half hour correcting your spelling and grammar, too!
*February 1, 2016*

**Math**

If I read your language correctly, there is a 5m border around the field. So, if the dimensions of the whole area is 130x85, then the field is 120x75.
*February 1, 2016*

**Math**

as usual, k∘d = k(d) = √(d^2+100) = √((35t)^2+100) assuming t is in hours.
*February 1, 2016*

**math**

NO! Read we wrote!!! The sides are 9 over √2
*February 1, 2016*

**math**

If the diagonal is d=x√2, then x = d/√2 you did d*√2 instead.
*February 1, 2016*

**Biology**

Wine is made by mixing yeast with grapes and allowing the yeast cells to undergo fermentation. Sparkling wine is a type of wine that contains high levels of dissolved carbon dioxide. What is the source of the carbon atoms in the carbon dioxide found in sparkling wine? ethanol ...
*February 1, 2016*

**Biology**

I'm sorry I meant c
*February 1, 2016*

**Biology**

What would most likely happen to cells placed in fresh water? a- water would flow out because they are hypotonic to the external environment b- water would flow into them because they are hypotonic to the external environment c- water would flow out of them because they are ...
*February 1, 2016*

**math**

assuming you want integer values, just find the factors of 389 Hmm. 389 is a prime number. So, just pick any value (x) for the width and the length is 389/x. I suspect a typo.
*February 1, 2016*

**chemistry**

HCl + NaHCO3 = NaCl + H2O + CO2
*February 1, 2016*

**Math**

That is correct.
*February 1, 2016*

**Geometry**

4(1)-4(-1)+2 = 4+4+2 = 10 ??
*February 1, 2016*