Saturday
April 19, 2014

Posts by Steve


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>>

Search
Members