Friday
December 9, 2016

Posts by steve

Total # Posts: 47,029

Algebra 1 A
money <= 100 cost for x gallons (16 cups/gal) = .20*16x + 2.33x = 5.53x sales: .50*16x = 8.00x profit: 2.47x
November 23, 2016

pre calculus
(u•v)(u + v) = (-1*4 + 7*(-3))<-1+4,7+(-3)> = (-25)<3,4> = <-75,100>
November 23, 2016

Calculus
f(-3) = f(3) = 0 The only horizontal tangent is at x=0.
November 23, 2016

business maths
annual interest is P((1+.06/2)^2-1) so, you need P(1.03^2-1) = 500 P = $8210.18
November 23, 2016

Calculus
f'(x) = (x^2)^2 (2x) - x^2 (1) = 2x^5-x^2 Google differentiation under the integral for several explanations. Wikipedia has a good article. This is really just the chain rule in reverse.
November 23, 2016

Math
4 1/2 = 18 * 1/4 so, 10 : 1/4 = 180 : 4 1/2
November 23, 2016

Calculus - fundamental theorems
The chain rule says that df/dx = df/du * du/dx. So, you have e^(x^3)^2 (3x^2) = 3x^2 e^(x^6) now, technically, you have to subtract f(u) at the lower limit, but since d1/dx = 0, it just goes away. wikipedia has a good article on this.
November 23, 2016

Calculus - Fundamental Thm of Calc
F' = f(x)dx/dx - f(1)d1/dx = t^3 - 0 = t^3
November 23, 2016

calculus
|<a,b>|^2 = a^2+b^2
November 23, 2016

maths
the LCM is probably 35 If the larger number is 210, then the ratio says that 5:7 = 150:210
November 23, 2016

Ptofit and Loss
with 12 oranges in a dozen, that makes them $5 each. So, ...
November 23, 2016

math
15x+9y=30 now subtract to eliminate y.
November 23, 2016

vertical motion physics
due to symmetry, the max height is reached after 5 seconds. y = vi*t - 5t^2 at t=5, v=0, so since v = vi - 10t, vi-10*5=0 vi=50 y = 50t-5t^2 y(5) = 50*5-5*25 = 125
November 23, 2016

Math
just plug in the numbers. Should not be too hard.
November 23, 2016

Math
http://www.wolframalpha.com/input/?i=%7B%7B1,3,2%7D,%7B2,-1,-3%7D,%7B5,2,1%7D%7D*%7B%7Ba%7D,%7Bb%7D,%7Bc%7D%7D+%3D+%7B%7B3%7D,%7B-8%7D,%7B9%7D%7D
November 23, 2016

precalculus
the entire circumference is 40*2? = 251.33 cm so, 227/251.33 = 0.9 of the whole circumference the angle is thus 0.9 * 2? = 1.8? radians 1.8? * 180/? = 324°
November 22, 2016

science
None. Fe contains no hydrogen.
November 22, 2016

Math
for a triangle in standard position, sinC = y/r since r is always positive, you must have y>0. That is QI and QII. Since cosC = x/r, you must have x<0, so QII You have a 7-24-25 triangle, so the terminal point of the hypotenuse lies at (-7,24). If you are new to this, ...
November 22, 2016

Math
csc? cos? = -1 1/sin? cos? = -1 cos?/sin? = -1 as with any angle, cos^2? + sin^2? = 1 In this case, cos? = -sin? tan? = -1 ? = 3?/4 or 7?/4 No idea at all? Hmmm. I cannot believe that the question was assigned, yet the material never taught!!!??? And have you never heard of ...
November 22, 2016

Algebra2
Expand the logarithmic expression. log8 a/2 My answer is log8a-log8 2
November 22, 2016

maths
clearly the scale is 1:3 So, multiply the diameter by 3.
November 22, 2016

Math iniqualties and versitiles
the first way involves distributing the 3 through the parenthesized expression. The second just illustrates the order of evaluation (inside the parens first), and has nothing to do with the distributive property.
November 22, 2016

Algebra
much better.
November 22, 2016

Algebra
nope. both wrong. What did you do? Find the vertex and the roots.
November 22, 2016

Math
actually, since you allow for 2 or more members, I'd say that all integer values can be formed using members of the set. In fact, using just {-1,0,1} will produce all integer values.
November 22, 2016

Math
all integer values from -8 to +8
November 22, 2016

Math
The curve for the line integral is just x = 9cos(t) y = 9sin(t) z = 0 Now just evaluate F.dr and integrate for t in [0,2pi]
November 22, 2016

Math
1/4 x = 28
November 22, 2016

Trigonometry
x/12 = cos40
November 22, 2016

English
1=2 3 I have never heard #3 I'd think: as opposed to "below" the mountain? 4 is ok
November 22, 2016

Math
I prefer D. No one is over 3 meters tall!
November 22, 2016

MATH
What do you do to check whether a number is rational or irrational? In your explanation, use an example of an irrational and a rational number.
November 22, 2016

Algebra
if there are breaks in the graph, the x-values at the breaks are excluded from the domain. If there is a minimum or maximum y-value, that sets the boundary on the range. Hard to believe you can't figure these, since you have the graph!
November 22, 2016

Math
0.8522727 MILES
November 22, 2016

Math (please check my answer!!)
you need another side, so since L is the included angle, I'd guess (D) since you need sides including L and M
November 22, 2016

English
all are good. recollect usually refers to a specific memory, not a general past.
November 22, 2016

English
I'd say device. It's a device with wings and engines. The whole mechanism is called an airplane.
November 22, 2016

math
it's an ellipse. x^2 + y^2/16 = 1
November 22, 2016

calculus help
y = r sin? x = r cos? r^2 sin^2? = r cos? r = cos?/sin^2? = csc? cot?
November 22, 2016

maths need help
log_9(a+3)-log_9(b) = c + (1/2) log_3(a-3)+log_3(b) =c - 1 (a+3)/b = 9^(c+1/2) (a-3)b = 3^(c-1) (a+3)/b = 3*9^c (a-3)b = 3^c/3 a+3 = 3b*3^(2c) 3(a-3)b = 3^c 3(a+3)(a-3)b = 3b*3^(3c) a^2-9 = 27^c a^2 = 9+27^c I expect you can get the rest.
November 22, 2016

Maths
well, since y=15-2x^2, just solve 3x+9(15-2x^2) = 1 18x^2 - 3x - 134 = 0 now just use the quadratic formula
November 22, 2016

Math
you sure you don't mean a^4 - 13a^2 + 36 ? let u = a^2 and try factoring u^2-13u+36 which two factors of 36 add to 13?
November 22, 2016

maths
The diagonals bisect each other, and also meet at an angle of 125°. So, the long side of the parallelogram can be found using the law of cosines. Let the parallelogram be ABCD and the center be E. AB^2 = 3^2+4^2 - 2*3*4*cos125° AB = 6.2262 Now, the altitude of triangle...
November 22, 2016

maths
(6/2)^2 * h = 2/3 (15/2)^3 h = 125/4
November 22, 2016

Maths
Hmmm. what two factors of 36 add to 13? Try factoring u^2-13u+36 and let u=x^2
November 22, 2016

Calculus
let u = cos(3x) and see what happens
November 22, 2016

Calculus
Good luck with this - an elliptic integral.
November 22, 2016

Math
well, there are 60 minutes in an hour, so just divide by 60. Hint -- it is not 56 mi/min
November 22, 2016

Math
Take a look here, and all will become clear. https://in.answers.yahoo.com/question/index?qid=20130823004513AAdmLmh
November 21, 2016

Math
If the roots are p and rp, then you have b/a = -(p+rp) c/a = p*rp see what you can do with that
November 21, 2016

Physics- Equilibrant Force
The resultant force is 71 NE So, the equilibrant force is 71 SW
November 21, 2016

Physics- Accleration of a Falling Penny
if the force increases (more upward) the the net downward force must decrease. So, (a) since F=ma
November 21, 2016

algebra
how about fixing the formatting?
November 21, 2016

dav chd
let x = w-1 x^4-4x^3+2x^2+4x+4 = (w+1)^4 - 4(w+1)^3 + 2(w+1)^2 + 4(w+1) + 4 ...
November 21, 2016

Econ math/logarithms
8 = 2^3 log8 = 3 log2 = 3*0.39 = 1.17
November 21, 2016

Gauss-Jordan elimination
fix your typo and visit http://www.gregthatcher.com/Mathematics/GaussJordan.aspx for all the details
November 21, 2016

Calculus
You know that lim sinu/u = 1 so, lim tanu/u = 1 (because lim cosu = 1) So, lim tan(7x)/x = lim (tan(7x)*7)/(7x) = 7 lim tanu/u where u7x = 7 or, using L'Hospital, lim tan(7x)/x = lim (7 sec^2(7x))/1 = 7
November 21, 2016

Trig
You know that the standard parabola x^2 = 4py has focus at (0,p) and directrix at y = -p. Your parabola has been shifted so its vertex is at (-2,6). 4p=8. So, the focus is 2 above the vertex and the directrix is 2 below the vertex.
November 21, 2016

math
Let the printed area xy=50 The total area is a = (x+2)(y+4) = (x+2)(50/x + 4) = 4x + 58 + 100/x so, find where da/dx = 0 (and x>0)
November 21, 2016

math
it is the slope of the line joining (1,f(1)) and (2,f(2)): (1,20/4) and (2,20/16) (20/16 - 20/4)/(2-1) = ?
November 21, 2016

Math
s shares at price p gives sp = 308 (s+6)(p-3) = 308 sp+6p-3s-18 = 308 308+6p-3s = 18 2p-s = 6 2p - 308/p = 6 2p^2 - 6p - 308 = 0 p^2 - 3p - 154 = 0 (p-14)(p+11) p = 14 s = 77
November 21, 2016

science
work = force * distance
November 21, 2016

Math
2,47
November 21, 2016

Math algebra
If the quicker person takes x hours, then the slower person takes 3x hours. 1/x + 1/3x = 1/4 12+4=3x x = 16/3 so, 3x = 16 hours for the slowpoke.
November 21, 2016

Math
looks good to me
November 21, 2016

Chemistry 20
Zn + CuSO4 = Cu + ZnSO4 same number of moles of each
November 21, 2016

Math
since column 1 is the one-times column, the row must be 4.
November 21, 2016

Physics
(a) v^2 = 2.5^2 + 4.5^2 (b) 2.5 (c) 4.5
November 21, 2016

Maths help asap please.
think: (a+1)^2 = a^2+2a+1
November 21, 2016

math
the + or - status does not matter. Just find the rule as usual.
November 21, 2016

maths
t = u+2 (10t+u) + (10u+t) = 88
November 21, 2016

Physics
well, 5min = 1/12 hr. Now use the hint.
November 21, 2016

Algebra pt. 2
That's better, but express them a as pair of coordinates. (12,4) not just 12 4.
November 21, 2016

maths
x+24 + 10 = 3(x+10)
November 21, 2016

Algebra
NO Take each point and double its coordinates. Stop trying to get rid of the coordinates. The problem says to come up with a new list of coordinates for the expanded diagram. (6,2) becomes (12,4)
November 21, 2016

Algebra
No, you multiply each coordinate by the scale factor: 2 That's what the scale factor is for. what can it possibly mean to multiply x-values by y-values? You are trying to convert a point into a number. Bogus...
November 21, 2016

mathematics
what? reposting after just 5 minutes?
November 21, 2016

maths
well, 6 = 72/12, so ...
November 21, 2016

Mathematics
Let the ages of France, Emma, Father be x,y,z. Then we have x = 2y x+y = z-12 z=30 So, start substituting till you can find y.
November 21, 2016

Algebar
you have a difference of two squares a^2-b^2 = (a-b)(a+b) where a = 9x^3 b = 5y^5 Now just plug and chug.
November 21, 2016

math
chain rule: (a) 4(x^2+1)^3 * 2x (b) not sure what you mean by "primitive" The extrema (max and min) can be found where 8x(x^2+1)^3 = 0
November 21, 2016

maths
22.5
November 21, 2016

Math
x-21 = 71-x
November 21, 2016

motion
Take a look at this example. It is very similar to yours. http://www.a-levelmathstutor.com/m-momimp-coeffrest.php
November 21, 2016

Math, Surds @Reiny got it
My bad. I read "diagonal" not "area"
November 21, 2016

Math, Surds
s = 60/?2 = 30?2 m well, a square has 4 sides, so ...
November 21, 2016

math
m-1/m ... what? I will say, however, that (m-1)^2/m^2 = ((m-1)/m)^2 (m^2-1)/m^2 = (m-1)(m+1)/m = (m-1)/m * (m+1)
November 21, 2016

Chemistry
Looks like 205g to me.
November 21, 2016

Maths
My bad. I should have said that when ?=1 we get the equation x^2 + y^2 +4x - 3 + 1(2x^2 + 2y^2 +4x -6y + 3) = 0 3x^2+8x + 3y^2-6y = 0 (x + 4/3)^2 + (y-1)^2 = 25/9 Now the three circles can all be seen to intersect at the same two points: http://www.wolframalpha.com/input/?i=...
November 21, 2016

Maths
When ?=1, we get the circle (x+2)^2 + (y-1)^2 = 5 The three circles can be seen at http://www.wolframalpha.com/input/?i=plot+x%5E2+%2B+y%5E2+%2B4x+-+3+%3D+0,+++2x%5E2+%2B+2y%5E2+%2B4x+-6y+%2B+3+%3D0,+(x%2B2)%5E2+%2B+(y-1)%5E2+%3D+5,+y%3D0,+x%3D0
November 21, 2016

Maths
Solving the system of equations x^2 + y^2 +4x - 3 = 0 2x^2 + 2y^2 +4x -6y + 3 =0 Is the same as solving the system x^2 + y^2 +4x - 3 = 0 ?(2x^2 + 2y^2 +4x -6y + 3) = 0 The equation x^2 + y^2 +4x - 3 + ?(2x^2 + 2y^2 +4x -6y + 3) = 0 can be written as (*) (1+2?)x^2 + 4(1+2?)x...
November 21, 2016

math-mechanics 1
(a) v = 2i (b) r = 2it + (-0.2i+.05j)t^2 (c) we want r to have a zero i component. So, 2t - 0.2t^2 = 0 0.2t (10-t) = 0 t=10 (d) v = 2i + (-.4i+.1j)t we want the i and j components to be equal, so 2-.4t = .1t 2 = .5t t = 4
November 21, 2016

Math
If the tree's height is x meters, the broken tree forms a right triangle with sides 12/25 x and 10. The hypotenuse is 13/25 x. 10^2 + (.48x)^2 = (.52x)^2 Now just solve for x.
November 21, 2016

Math
well, how many months in 4 years? 423 each month...
November 21, 2016

algebra 1
x = 7y/4 + 3/4 y = 4x/7 + 3/7 x = -3y/4 - 7/4 y = -4x/3 - 7/3
November 20, 2016

Math
-1
November 20, 2016

MATH
:DDDDDDDDDDDDDDD
November 20, 2016

MATH
So to restate it in this account that I have been asking the questions and was granted your help. Oh wow that is interesting Ms. Sue and I want to do that with my life also, but sometimes I need some light on how to do these problems. The question I got wrong was a question I ...
November 20, 2016

MATH
Sorry Ms. Sue I had logged on to my account and answered your post on that account but it was really me STEVE as Your best friend
November 20, 2016

MATH
THANKS MS. SUE I got 21/22 questions correct I HATE THAT I WANT 22/22 my mom will get really mad so I have to correct the problem I got wrong before she finds out but thank you for the help for the rest of the questions
November 20, 2016

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