Saturday

April 19, 2014

April 19, 2014

Total # Posts: 21,776

**calculus**

check your graph against this one: http://www.wolframalpha.com/input/?i=tan%28x%29+for+5pi%2F3+%3C%3D+x+%3C%3D+3pi

**Algebra 1**

pick any x, say 5, and plug it in: 4*5 + 3y = 14 now solve for y 20 + 3y = 14 3y = -6 y = -2 So, (5,-2) is a solution Now just do some more. You can also pick a y value and then solve for x.

**math**

p - .20p = 56 .80p = 56 p = 70

**math**

1.5/w = 5/19

**Geometry**

Not sure where the typo is, but assuming you meant 7 and not 12, your reasoning is correct. You can do it the way you did, subtracting the larger from the smaller, or you can do |7 - (-15)) = |7+15| = 22 Personally, I prefer subtracting the smaller, but...

**calculus**

for even values of n > 0 f has a min for odd values of n > 1, inflection

**math**

not sure of your notation. try using ^ for exponents, as in x^2 or y^3 If you want a root, try using the special characters √ ∛ ∜ or use fractional exponents: x^1/2 for square root, etc. or, use a recognizable function name such as sqrt(x) cuberoot(x) 4throot...

**Math**

.04x + .03(15000-x) = 550

**math**

h/200 = tan 60°

**math**

94 - 40

**algebra**

2(26+h) < 180

**math**

that would be 28.05/3 kg

**math**

x/32 = 3/4

**math**

check the differences: 3,6,9,12,15 ... Now it should be clear.

**math**

18/12 s/s t^5/t^3 = 3t^2/2

**math**

4y + xy = 2 4y' + y + xy' = 0 y' = -y/(x+4) Now you can use the quotient rule or another implicit differentiation. 4y" + y' + y'^2 + xy" = 0 So, now just plug in (-3,2) to evaluate it there.

**Calc Help :(((((**

why would I want to help so you "can't do the rest"? I'd hope you can do the rest! Anyway, we all know that 1/∞ = 0 (or that the limit if 1/x as x->∞ is zero), so divide both polynomials by the highest power of x in either, to get (a + b/x^2) /...

**Chemistry**

the molecular mass in grams is the mass of mole. For example, since C has mass 12 amu and O has mass 16 amu, one mole of CO2 has mass of 12+2*16 = 44g 1M solution is 1 mole/1 liter

**HELP**

since 4B = A with a carry, B > 2 and A is a multiple of 4. Since 4A plus the carry generates no carry, 4A < 9 or A <= 2 So, I'd say A=2 and B can be 3 or 8, but 4*28 is 3 digits, so we have 23+23+23+23 = 92

**calculus**

r = ln (x+2)/(x-1) (x+2)/(x-1) = e^r x+2 = e^r x - e^r x(2-e^r) = -e^r x = e^r/(e^r-2)

**math**

Since there are 4 colors, even if the 1st 4 marbles are all different, the 5th marble must be the same color as one of them.

**Mat/116**

ummm. all points (x,y) where y=2x-3.

**math**

.035 * 200 = ?

**algebra**

just do the steps normally taken to solve equations -2 < 2x-4 < 4 add 4 throughout to get 2 < 2x < 8 now divide by 2 to get 1 < x < 4

**English**

#2 haven't forgotten (didn't forget would have been correct) The others are ok.

**algebra**

assoc prop of mult. Also, it's commutative, not communicative!

**math**

1.5 * 1.1^n is NOT 1.65^n That's like saying 2*3^2 = 5^2 Also you are saying that 1.5(-1) = .5 The correct algebra is 100=1.5((1.1^(n) - 1))/(1.1-1) 10 = 1.5(1.1^(n) - 1) Now divide by 1.5 20/3 = 1.1^n - 1 23/3 = 1.1^n n = log(23/3)/log(1.1) = 21.37 or 22 if you round up t...

**add maths**

as you know, the vertex of a parabola is at x = -b/2a. In this case, that will be at x = 12/6 = 2. So, find f(2)

**Probability**

Consider the AB combination as a single letter. Then there are 4!=24 ways to arrange the letters AB,C,D,E. Since A-B can be arranged in two ways, there are 2*4! = 48 ways.

**Math**

not sure what "this" refers to. Radicals and linear equations are separate topics. First step: google the terms you are interested in. You will find a wealth of discussions, far beyond you will find here.

**Math**

5040 + .30p = p p = 5040/.7 = $7200

**math**

I'd say 48000 * (.18+.124+.029) / 4 = 3996

**algebra**

-2(2x+9)>-4x+9 -4x-18 > -4x+9 -18 > 9 what do you think?

**Math**

you have correctly determined that y = -(x-2)^2 (x+2) You know the graph crosses the axis at x = -2 and that it just touches the x-axis at x=2 (because of the double root) Since for large negative values of x, all 3 factors are negative, y > 0 for x < -2 So, y < 0 for...

**Physics**

a = (110-77)/16 = 33/16 m/s^2 displacement during that time is s = 77*16 + 33/32 * 16^2 = 1496 m

**Math**

72 = 2^3 3^2 99 = 3^2 11 54 = 2 3^3 LCM(72,99) = 2^3 3^2 11 = 792 LCM(72,54) = 2^3 3^3 = 216

**Algebra**

you are correct as you surely verified, by using the values in the equations ???

**Algebra**

I think you must have meant -13 and 16. If so, then your algebra isn't entirely useless.

**Algebra**

no ideas at all? Let the numbers be x and y Now, what do you know about them?

**Math**

how does the heart shape relate to the circle and square?

**Math**

Eh? 72 - 5(13+2)*5 72 - 5(15)*5 72 - 75*5 72 - 375 -303

**alg 2**

I can only assume you mean (m•n)^-1 = 1/(m•n)

**Maths**

Yeah, it's kind of tricky. Using 6,1 for factors will make things kind of lop-sided, so I'd go with 2 and 3. (5x-2)(x+3) = 5x^2 + 13x - 6 Nope (5x+3)(x-2) = 5x^2 - 7x - 6 Nope I think we're out of luck. The discriminant is 64+120 = 184, which is not a perfect squar...

**Math**

well, 4,000,000 has 6 zeros. 40 has 1 zero. So, if you need to add 5 more zeros, which multiplier has 5 zeros?

**Algebra**

If the 1,2,3 pointers are in amounts of x,y,z, then x+2y+3z = 95 x+y+z = 54 y = x+16 (x,y,z) = (17,33,4)

**math**

33.60/4 * 1000

**algebra**

12n ≤ 15

**Algebra 1**

initial velocity v is zero - it just fell initial height is 16 feet, so h = -16t^2 + 16 So, you want to find t when h=0 (apple hits the ground) -16t^2 + 16 = 0 -16 (t^2-1) = 0 -16(t+1)(t-1) = 0 So, the apple's height is zero when t=1; that is, one second after being dislod...

**Algebra 1**

Ahem. h = -16(2)^2 + 47(2) + 3 You do not have -(16*2)^2, you just have -16 * 2^2 = -16*4 So, h(2) = -64 + 97 = 33 Ball hits the ground when h=0, so -16t^2 + 47t + 3 = 0 -(t-3)(16t+1) = 0 t = 3

**Algebra 1**

your answer is right, but your units are not The volume is 2500 ft^2 * 10 ft = 25000 ft^3 25000 ft^3 * 1gal/(0.134 ft^3) = 186567 gal

**Algebra 1**

If the moat has width m, castle area = 45*60 = 2700 castle+moat area = (45+2m)(60+2m) since there is moat on both sides. moat area = (45+2m)(60+2m)-2700 Now plug in your value for m, and recall that volume is area * depth

**Math**

so, area = x^2 + 4x(v/x^2) = x^2 + 4v/x Now just find when that is a minimum

**Algebra**

all correct. Good work. Lots of students don't understand why we always set the polynomial equal to zero to find solutions. You seem to understand that quite well.

**Algebra 1**

It's neither. z^2 + 15z + 54 = (z+6)(z+9) z^2 - 15z + 54 = (z-6)(z-9) z^2 + 15z - 54 = (z+18)(z-3)

**Algebra 1**

looks good to me

**algebra**

Looks like each number is 1/2 the previous one. So, what is 1/2 of -6?

**algebra**

well, it looks associative So, are you adding or multiplying? By the way, that's commutative, not communicative. Pay atten--, I say, pay attention, boy...

**algebra**

well, what's 3*5 / 5*3 ?

**gobbledegook**

Your table is suffering from browser formatting. However, you do need to recall that (fg)' = f'g + fg' gather those data from your table and you should be able to fill in the blanks.

**Physics**

since weight varies as 1/distance^2, r^2/(r+d)^2 = .99 r/(r+d) = √.99 r = √.99r + √.99d r(1-√.99) = √.99 d r/d = √.99/(1-√.99) = 198.5

**algebra**

associative prop of mult

**algebra**

nope. 1/3 < 2/5, but -1/3 > -2/5 Plot them on the number line and see which is on the right.

**algebra**

integers

**Math**

I'd say that a 10% raise on a base pay of $3000/mo is 10% of 3000, or $300/mo

**Physics 2**

A beam of light is incident on a plane mirror at an angle of 35¨¬. If the mirror rotates through a small angle ¥è through what angle will the reflected ray rotate

**Physics 2**

An antenna is connected to a car battery. Will the antenna emit electromagnetic radiation? Why or why not? Explain where Amperes and Faradays law is concerned

**algebra**

x-8 >= 20 None of the choices is right. "at least 20" means 20 or more -- greater than or equal to.

**Algebra 1**

as you know, area = width * length area = w*(2w+4)

**Algebra 1**

#1 ok #2 ok #3 8 (x^2 is the highest power, so goes first) Although since you have 5x-2x I suspect a typo. If you meant -2x^3, then your answer is ok. #4 ok #5 ok, if x is replaced by w #6 ok #7 no: -6-(-8) = +2 #8 ok #9 no. (3x-4)(3x-4) = 9x^2-24x+16 square the 1st and last v...

**algebra**

if you mean s = 3r+4t, t = (s-3r)/4 Hmm. Nope. Maybe you mean s = 3r^4 t t = s/(3r^4) at least that choice is there.

**math**

once past the window, the rock spent .8 seconds going up and .8 seconds going down. So, the rock spent 1.2 seconds going up. since v = Vo-32t and v(1.2)=0, Vo-32(1.2)=0 Vo = 38.4 Doesn't matter how high the windows is, though its location is determined by the time interval...

**math**

(11000-8690)/11000 * 100 = 21%

**precal**

I hope one of the choices was y=5

**Math**

for any value of x, f(x) = -5x+1 So, wherever you see an x, substitute a -2 and you have f(-2) = -5(-2)+1 = 10+1 = 11

**Algebra 1**

#1 nope. If you subtract -3 from 9, you don't get 6. 4 x 10^12 #2 yes #3 (4y^6/x^3)^2 = 16y^12/x^6 #4 yes

**Calculus**

And you arrive there by using partial fractions: 1/(x^2-1)^2 = 1/4 (1/(x+1) + 1/(x+1)^2 - 1/(x-1) + 1/(x-1)^2)

**Calculus**

x^3/(x+1)^2 = x - 2 + 3/(x+1) - 1/(x+1)^2 Now it's a piece of cake. ... Right?

**Calculus**

That pesky y' gets in the way. The solution is really y = c1 e^x + c2 - 1/2 (sinx - cosx)

**Math**

since p/d is constant, 30/80 = p/50

**Algebra 1**

#1 nope. If you subtract -3 from 9, you don't get 6. 4 x 10^12 #2 yes #3 where did b come from? I suspect you mixed up problems. (4y^6/x^3)^2 = 16y^12/x^6

**precal**

the domain is all reals. e^z is never zero, so we don't have to watch out for that. Unless your typo conceals the fact that you means f(x) = 2 + 1/(e^(x/3)-5) In which case we cannot have e^(x/3)-5 = 0 e^(x/3) = 5 x/3 = ln 5 x = 3 ln 5 = ln 125 For the inverse, swap variab...

**Algebra**

Your post so far: 0 words. Whattaya got? In your own words, that is.

**phisecs**

final displacement is 8 km in 3 hrs, so v = 8/3 km/hr North His speed, on the other hand, is non-directional, so it is just distance covered = 18/3 = 6 km/hr

**Grammar**

"are" is correct. FWIW, I thought the first post was ok. The "there" isn't really necessary. The structure is simply Trapdoors into the dungeons are at the end of some passages.

**Geometry - incomplete**

what do you mean "A=14" ? A is a point or and angle.

**Geometry**

learn to recognize common triangles. 5-12-13 is one of them. Now everything should be easy. Come back if not. Might as well show your work while you're at it . . .

**Geometry**

assuming the figure is a rectangular prism, you know that volume = length x width x height. Just plug in the data given.

**math**

just divide what you have: (3/10)km / (7/12)L = (3/10 * 12/7) km/L = 36/7 km/L

**Math**

on the other hand, rate usually involves a time period, as in km per hour ft per second So, I think I'd have to change my answer to ratio, the ratio of points to games.

**Math**

rate The "per" usually indicates a rate, as in miles per gallon population per square mile

**Calculus**

y = cx + x ln^2(x)

**Intermediate Algebra**

If the 1,2,3 pointers are in amounts of x,y,z, then x+2y+3z = 95 x+y+z = 54 y = x+16 (x,y,z) = (17,33,4)

**algebra**

well, what is y-0=2000?

**Math**

Hmmm. The integers are . . . -12 -11 -10 -9 -8 -7 -6 . . . What do you think?

**Math**

recognize the 3-4-5 triangle scaled up to 6-8-10?

**algebra**

if you add some spaces, it should be clear: 2x/5 - 9 + 9 OK?

**math**

It occurs to me that I may have misinterpreted the unseen diagram. If the 70° angle is on the face of the pyramid, then we have h/(b/2) = tan 52° and the slant height s is in the other triangle, rather than just h, so √((b/2)^2+h^2)/√(b^2/2 + h^2) = sin 70&...

**math**

looking perpendicular to one face of the pyramid (base a square of side b, and height h), h/(b/2) = tan 52° looking up the edge, h/√((b^2/2 + h^2) = sin 70° Clean things up a bit, and you can solve for b and h

**algebra**

it's the equation of a line in the x-y plane.

**Algebra**

3x + 4(3-x) = 25

Pages: <<Prev | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | **17** | 18 | 19 | 20 | 21 | 22 | 23 | Next>>