Sunday

June 26, 2016
Total # Posts: 41,431

**Math; Solve by Graphing**

clearly D is out, since it has nothing to do with the solution. Similarly, B and C are out, because it does not matter where the lines hit the axes. The solution is where both equations are true. Since each represents a line, that is where the lines intersect. So, (A) is the ...
*May 23, 2016*

**Math**

first, review what complementary and supplementary mean. An angle and its complement sum to 90 degrees. So, what number do you add to 52 to get 90? similarly for supplement.
*May 23, 2016*

**analytic geometry**

The two lines you named are parallel. They cannot be the asymptotes of an hyperbola.
*May 23, 2016*

**math**

c = kq
*May 23, 2016*

**Geometry,Math**

you are correct that a cylinder has less surface area than a rectangular prism.
*May 22, 2016*

**Math**

A farmer has dogs and chickens running around in his backyard. There are a total of 36 animals, and the farmer counts a total of 56 legs. The farmer can use a system of equations to determine how many of each animal there are. He claims that one of the equations in the system ...
*May 22, 2016*

**Math**

total marbles = 22 so, P(blue,yellow) = 9/22 * 13/21
*May 22, 2016*

**science**

well, rice grains are bigger than sugar grains. So just use a fine sieve. Sugar goes through, rice stays behind.
*May 22, 2016*

**Math**

A farmer has dogs and chickens running around in his backyard. There are a total of 36 animals, and the farmer counts a total of 56 legs. The farmer can use a system of equations to determine how many of each animal there are. He claims that one of the equations in the system ...
*May 22, 2016*

**grade 9**

28*22*h = π*3.5^2*40 h ≈ 2.5m
*May 22, 2016*

**Math**

A farmer has dogs and chickens running around in his backyard. There are a total of 36 animals, and the farmer counts a total of 56 legs. The farmer can use a system of equations to determine how many of each animal there are. He claims that one of the equations in the system ...
*May 22, 2016*

**Easy Math**

I think you are correct. If the points in order are A,B,C then each point can be the start of a ray, and each ray can go in two directions. But rays from A and C must also include B. So, the rays are AB (or AC, which is the same) BA and BC CB (or CA)
*May 22, 2016*

**pre-algebra**

there are infinitely many possible values: 2(30+L) >= 768 30+L >= 384 L >= 354 so, any number at least 354 will work. I suspect you did not ask the right question.
*May 22, 2016*

**Algebra**

2(w + 3w-4) = 48 find w, and then you can get the length.
*May 22, 2016*

**integral calculus**

Draw a cross-section. If the oil is at depth y, then the width of the thin rectangle of oil is 2x, where (3-y)^2 + x^2 = 9 x = √(6y-y^2) So, the weight of oil for that thin sheet is 2x*8*60 dy and the total work to lift all the oil out of the top of the tank is thus &#...
*May 22, 2016*

**maths**

Fix the typo (ax^2+bx+x ?), and is the curve tangent to the line?
*May 22, 2016*

**math**

assuming the strides take the same amount of time, the dog wins. 1.30 * 0.70 = 0.91
*May 22, 2016*

**Mathematics**

well, S10 = 10/2 (1+19)
*May 22, 2016*

**math (check answer)**

why would the math class have students whose birthdays are skewed?
*May 21, 2016*

**math**

since the events are independent, just multiply their probabilities. For the first, that would be 1/6 * 1/2 and the others likewise
*May 21, 2016*

**Math**

just crank out the algebra. The result is 4 note that w = cis(2pi/3) or cis(4pi/3)
*May 21, 2016*

**expansion help**

scroll down and down at http://www.wolframalpha.com/input/?i=%281%2B%281%2Fx^3%29%29
*May 21, 2016*

**Math**

f+s = 72 f+2 = 3(s+2)-4 now just crank it out.
*May 21, 2016*

**Math**

4 hours = 240 minutes. So, the fraction of the tank filled in one minute is 1/15 - 1/240 = 15/240 = 1/16 So, it will take 16 minutes to fill the leaking tank
*May 21, 2016*

**geometry**

an unusual position -- the ladder is not on the ground. I expect you mean the foot of the ladder is one meter from the wall. I assume you want the height of the top of the ladder. If the height up the wall is h, then 1^2 + h^2 = 20^2
*May 21, 2016*

**Middlesex**

recall that if a is a root, then (x-a) is a factor of f(x). So, you have (x-3)(x+6) = 0
*May 21, 2016*

**ordinary differential equation**

well, it's clear that (m-3)^3 = m^3 - 9m^2 + 27m - 27 now just proceed as usual to solve this type of equation.
*May 21, 2016*

**math**

depends on the distance, no? But, you know that after n seconds, the distance traveled will be Sn = n/2 (2*1.5+0.4(n-1)) cm
*May 21, 2016*

**math**

z = 1250ln(yx^2)+45(y^2+x)(x^3 -2y)-(xy)^1/2 see ∂z/∂x at http://www.wolframalpha.com/input/?i=1250ln%28yx^2%29%2B45%28y^2%2Bx%29%28x^3+-2y%29-%28xy%29^1%2F2 But you will need some values for x and y if you want a numeric value.
*May 21, 2016*

**Maths**

surely you can plot each of these curves. But just to remind you, http://www.wolframalpha.com/input/?i=plot+y%3Dsinx,+y%3Dcosx,+y%3Dcosx-sinx
*May 21, 2016*

**logarithm math-need help!!!!**

If we let u = log_4(x) then x = 4^u and we have 5u + 48/u = 4^u/8 the solution to this is u=4 so, x=4^u = 256
*May 21, 2016*

**math**

a factor of 1000 means that one 6 is 3 places to the left of the other. That is, the number must contain the digit string 6336 That means that the other 3 must go on the left or right end.
*May 21, 2016*

**Mathematics**

w(w+3) = (w/2)(w+3 + 5) w = 2 be sure to check that this works.
*May 21, 2016*

**geometry**

dv/dt = 4πr^2 dr/dt da/dt = 8πr dr/dt (dv/dt)/(da/dt) = r/2 so, when r=10, da/dt = 240 cm^2/s
*May 21, 2016*

**Math**

a mess, is what. Still, I will try to parse your garbled sentence. 9 - 3 ÷ 1/3 + 1 = 1 If that's not what you meant, try using some parentheses to get what you want.
*May 21, 2016*

**maths**

original: (d-3)/d now, adding 1's, we have (d-3+1)/(d+1) = 5 Hmmm. I suspect a typo, since d is not an integer.
*May 21, 2016*

**math**

$(40*0.90-10)*1.45 = $37.70
*May 20, 2016*

**math**

clearly the numbers in question must have 6336 so, there are two 3's left over, which must go on the ends: 36336 63363
*May 20, 2016*

**Algebra**

you show B and D the same. Pick the one which is really 6^x x^6 is not what you want. That is (0,0),(1,1),(2,64)...
*May 20, 2016*

**math**

oh come on. either 4cotx+3 = 0 cotx = -3/4 or cotx-1 = 0 cotx = 1 In the first case, x will be in QII or QIV on the second case, x will be in QI or QIII
*May 20, 2016*

**math**

since csc^2 = 1+cot^2, 4(1+cot^2x)-7 = cotx 4+4cot^2x-7 = cotx 4cot^2x - cotx - 3 = 0 (4cotx+3)(cotx-1) = 0 Now it's easy, right?
*May 20, 2016*

**Algebra**

1*57 + 6*x = 5(57+x)
*May 20, 2016*

**pre-algebra**

x + 1/3 x = 84 4/3 x = 84 ...
*May 20, 2016*

**HELP ME ! DESPRATE MATH STUDENT !!**

you cannot compare those integers with 6 1/3 ? You are in deep doodoo. At the very least, grab a calculator and subtract each from 6.333333 If the result is positive they are less; if negative, they are greater.
*May 20, 2016*

**HELP ME ! DESPRATE MATH STUDENT !!**

well, geez, did you try a few values? 3*0 - 4 <= 15 ? 3*6 - 4 <= 15 ? and so on. or, algebraically, 3x-4 <= 15 3x <= 19 x <= 19/3 so, how many of those values fit the bill?
*May 20, 2016*

**math**

original value: n/d new value: 1.60n/0.80d = 2n/d so, it has grown by 100%
*May 20, 2016*

**math**

5/300 x = 475/100
*May 20, 2016*

**math**

6/5 as many people, so 5/6 as much time
*May 20, 2016*

**math**

195/15 * 8
*May 20, 2016*

**math**

v/i = 5/2, so v = 5i/2 v = i+42 5i/2 = i+42 so, i=28 and v=70 You want to find x such that (70-x)/(28+x) = 3/4 I expect you can handle that part.
*May 20, 2016*

**math**

420/5 = 84 so, multiply all the values by 84 and you have 504:420:252 Now just add all that up.
*May 20, 2016*

**math**

15 + x = -84 ...
*May 20, 2016*

**MATH HELP PLEASE !!**

clearly, it also increases by 5 (x+5)-3 = (x-3)+5
*May 20, 2016*

**Math (Vectors)**

the angle θ between the vectors is 55-25 = 30°. u•v = |u|*|v|*cosθ now just plug in your numbers.
*May 20, 2016*

**Math/ Ratios**

ratios are just fractions. So, you have a = h (a-23)/(h-7) = 3/4 now just solve for a,h and then a+h
*May 20, 2016*

**Pre Algebra**

5C 6D 9 correct 16C 19B 20A 21C Review your methods and try them till you get these answers.
*May 20, 2016*

**MATH FACTORING**

does not factor with real numbers. The discriminant is negative.
*May 20, 2016*

**Math Help!!**

well, is there any chance of rolling a zero?
*May 20, 2016*

**pre cal**

y = 4√(2x/3) - 1 y+1 = 4√(2x/3) just square both sides and you have y^2+2y+1 = 16(2x/3) That is clearly a parabola opening to the right.
*May 20, 2016*

**calculus**

why all those useless words? Use some math symbols! dy/dx = 3y/x dy/y = 3/x dx lny = 3lnx + c or, lny = ln(x^3) + ln(c) (different c) y = cx^3 y(1)=1 means c=1 y = x^3 I expect that you can determine the domain for that...
*May 20, 2016*

**math**

looks right to me.
*May 20, 2016*

**Algebra**

while 40 = 40*1, 20 ≠ 40*2 so, your first guess is wrong. However, note that x*y=40 for all the items.
*May 20, 2016*

**trigonometry**

I'll just use x for the angle sin^2(x)/(1-cos(x) = (1-cos^2(x))/(1-cos(x)) = (1+cosx)(1-cosx)/(1-cosx) = 1+cosx
*May 20, 2016*

**math**

of course you do. The perimeter was in inches -- so are the sides. Of course, you could use cm or miles or chains or light-years, but then the numbers would no longer be integers.
*May 20, 2016*

**Calculus (Integration proving)**

can you clarify what (integral, r to none) means? and if you only have dA, why the three dimensions for R?
*May 20, 2016*

**math**

hmmm. good point.
*May 20, 2016*

**math**

do you know the dimensions of a football field?
*May 20, 2016*

**math**

4(x+1)(x+2) = 24 (x+1)(x+2) = 6 I think you know two consecutive integers whose product is 6.
*May 20, 2016*

**Math**

#1 ok #2 ok so, #3 must be ok too, since it is the same as #2!
*May 20, 2016*

**math**

(x + 1/x)^2 = x^2 + 2 + 1/x^2 = 49 so, x + 1/x = 7 or -7
*May 20, 2016*

**calculus**

even without calculus, this one is easy. The x-intercept of y=2x+a is x = -a/2 So, you have a triangle with base 3a/2 and height 3a, so the area is 9a^2/4. If 9a^2/4 = 18, a = √8 check: ∫[-a/2,a] 2x+a dx = 9a^2/4
*May 20, 2016*

**Trigonometry**

Draw a diagram. The 14.6m part and the 4.4m part form two sides of a triangle. You want the 3rd side. Using the law of sines, 14.6/sin50° = 4.6/sinB now you have one more angle, so the 3rd angle C is easy to find, and the side you want is now easy. c/sinC = 14.6/sin50°
*May 19, 2016*

**math**

none. each side must be less than the sum of the other two. 9 is too long. The sides of 7 and 1, laid down completely flat don't reach from one end to the other.
*May 19, 2016*

**Pre-Calc**

draw the triangle. sin = y/r cos = x/r
*May 19, 2016*

**math**

did you try plotting the points? Note that the line from (0,0) to (4,0) is horizontal the line from (0,0) to (0,4) is vertical there are two kinds of triangle that cold be named.
*May 19, 2016*

**math**

only one: a right triangle.
*May 19, 2016*

**math . someone please explain**

a negative exponent changes to positive when it's swapped from top to bottom That is, x^-4 = 1/x^4 1/x^-4 = x^4 and, raising powers to powers multiplies them. So, your fraction can be written as (x^4y^4z^4)^4 / (-3x^-4y^-2) = x^16y^16z^16 / (-3/(x^4y^2)) = (x^16y^16z^16)(x...
*May 19, 2016*

**Math Trignometry**

Let x = distance from Ray to the point under the plane h = height of plane You can see from the diagram that (h-800)/(5280+x) = tan67° h/x = tan81° Now just eliminate x and solve for h. I get 21,119 (c-800)/tan(67°) -5280 = c/tan(81°)
*May 19, 2016*

**Algebra**

the average rate of change is just (f(10)-f(2))/(10-2) so, plug and chug.
*May 19, 2016*

**Math**

sin = y/r cos = x/r, so sec = r/x so, plot the triangle, find the missing side (x) and plug it in.
*May 19, 2016*

**Math**

well, 16 = (20/5)^2 you're going to have to have a log5 in there somewhere.
*May 19, 2016*

**Algebra II**

b^2 = 81-25 find the angles using your standard trig functions; you have all three sides.
*May 19, 2016*

**Pre Algebra**

I'll do #1 -- the others you can do the same way, and we can check your answers. Just use the distributive property and the commutative properties. 18x^2+4x-15x^2-4+13x = 18x^2-15x^2 + 4x+13x - 4 = (18-15)x^2 + (4+13)x - 4 = 3x^2 + 17x - 4
*May 19, 2016*

**Please answer these questions Algebra 1**

#18 x^2-4x+1 = 0 x = (4±√20)/2 = 2±√5 #19 Hmmm. You don't say what models you have been using. Arranging the points from left to right, we have x y ------ -3 3 -2 0 -1 -1 0 0 1 3 The symmetry makes me want to try a quadratic with vertex at (-1,-1...
*May 19, 2016*

**Math -rational exponents**

root(3,12m^2) Not sure why you have two arguments to root. Do you mean cube root? If so, then you just have 12^(1/3) m^(2/3) Then nth-root is just the (1/n) power. Plug it in and then just use the normal exponent operations.
*May 19, 2016*

**math**

you are correct.
*May 19, 2016*

**math**

gee, impatient much? You are incorrect. Of the 9 tosses, how many are odd? You must have miscounted.
*May 19, 2016*

**Math - correction**

I misread the problem. If we label the bottom of the pole B, then BT cot68 = (BT-20) cot28 Both those expressions give BP, the distance between the building and the pole. To get PT, then, PT^2 = BP^2 + BT^2
*May 19, 2016*

**Math**

draw a diagram. Review your basic trig functions. PT cot68 = (PT-20) cot28
*May 19, 2016*

**math**

correct.
*May 19, 2016*

**math**

That would just be 1.43/1.09 * 10^(15-12)
*May 19, 2016*

**Math**

The equation is incorrect. Fix it and balance it.
*May 19, 2016*

**Math**

50+60+70-24-x = 100 Draw your Venn diagram to see why.
*May 19, 2016*

**Math**

actually, that should be 3x
*May 19, 2016*

**Math**

70+30+50-44-x = 100
*May 19, 2016*

**2nd year Spanish**

looks good to me.
*May 19, 2016*

**Math**

all look good
*May 19, 2016*

**Math Help- Areas!!!!**

assuming the width is the diameter, then the radius is half that. Since a = 2πr(r+h), that gives 350π and 522π
*May 19, 2016*

**Algebra**

x^2+y^2 = 3xy-20
*May 19, 2016*

**Math**

It is certainly possible, but by no means necessary. The IVT only applies to continuous functions, and money comes in discrete steps. Ellie might have gone from having $102.37 to only having $93.18, depending on what she bought. Or, she might have spent $195 on one item, and ...
*May 19, 2016*