# Posts by Steve

Total # Posts: 54,295

math
no problem. Average speed is total distance / total time: (45+20)km/(3 + 3/2 + 3/2)hr = 65/6 km/hr

Math
If A takes a days, B takes b days, b = a/2 C takes c days, c = a/3 1/a + 1/b + 1/c = 1/2 1/a + 2/a + 3/a = 1/2 6/a = 1/2 a = 12

Calculus
v(t) = v0 - 9.8t see what you can do with that...

Calculus (Volumes)
why switch names?

Calculus
The base is enclosed by the two parabolas, each with roots at (-1,0) and (1,0) The lower base B lies between the curves, with length 2(1-x^2)-(1-x^2) = 1-x^2 Using symmetry, then the volume is 2?[0,1] (B+b)/2 * h dx = 2?[0,1] ((1-x^2) + 1/2 (1-x^2))/2 * 2(1-x^2) dx = 2?[0,1] 3...

math
Hard to say. What's x supposed to be?

Math
2/(2+3+5) = 2/10

Math Review HELP
(3.5*10^3)(4.2*10^5)+(4.3*10^-4)(2.1*10^-2) = (3.5*4.2)*10^(3+5) + (4.3*2.1)*10^(-4-2) = 14.7*10^8 + 9.03*10^-6 = 1470000000 + 0.00000903 = 1470000000.00000903

math
It seems we can assume that lim(x?3) f(x) = f(3) In that case, we have 3f(3) + f(3)*4 = 35 7f(3) = 35 f(3) = 5

math
what does unit 27 mean? also, since a product involves two numbers, I don't get product of two digit number is 2117

Emergent computer tech
looks good to me. perhaps a better subject would have been HTML.

Math
The reciprocals form an AP, so for that sequence, a+3d = 11 a+23d = 23/3 a = 23/2 d = -1/6 Now you can find the desired terms: H7 = 1/(a+6d) H19 = 1/(a+18d)

Math
without some way to change her red chips to black ones, it's hard to say. Or, she can write an IOU -- in effect, borrow some black chips till the final reckoning is done.

maths
ages now: a,v ages next year: a+1, v+1 So, a = v+10 a+1 = 2(v+1) ...

Algebra
x/3 + x/2 = x-12 5/6 x = x-12 -1/6 x = -12 x = 72 check: 24+36 = 72-12 yep.

English
Which two readings portray the most similar pair of protagonists? "The Seafarer" and "The Wife's Lament" "The Wanderer" and "The Death of Beowulf" "The Wife's Lament" and "Grendel's Mother" "The ...

English
In The Seafarer, who or what is said to issue threats of illness, age, and an enemy's sword? a- God b- the sea c- the devil d- fate my answer is d

English
thank you

English
Which of these explains why Beowulf removes the head of the already dead Grendel? a- it was a final act of mercy b- It was a desperate attempt to escape. c- It was an additional act of revenge. d- It was an angry admission of defeat. my answer is C

math
the side length is ?500 the square has 4 sides, so ...

Multiplevariable calculus
cylindrical coordinates are just the regular polar coordinates, with z attached. Try ?[0,2?]?[1,?3]?[r^2,3] r dz dr d?

Math
n^2 + 3n = 18 n^2 + 3n - 18 = 0 so, what are two factors of 18 that differ by 3?

math
24/3 = 8 sets of books at \$5 each. That's \$40 so, Joe started with \$42

Math
parallel lines have the same slope perpendicular lines have slopes which are negative reciprocals. That is, m1 * m2 = -1 The line x-y=0 has slope=1 so, the point-slope form of the line you want is y+2 = 1(x-3) to change that to slope-intercept form, you want y = mx+b, so it&#...

Algebra
3x^-2y^-5 = 3 / x^2y^5 or, maybe it is (3x)^-2. in which case it is 1 / 9x^2y^5 when talking math, use math, not words ...

algebra
Susannah purchased ski equipment for \$978 using a six-month deferred payment plan. The interest rate after the introductory period is 21.45%. A down payment of \$150 is required as well as a minimum monthly payment of \$75. What is the balance at the beginning of the seventh ...

Geometry
MN+NP=MP 17+3y = 5y+9 Now just find y, and then you'll have MP.

math sequence
a(1) = 1 a(2) = 3a(1)-1 = 3-1 = 2 a(3) = 3a(2)-1 = 6-1 = 5 a(4) = 3a(3)-1 = 15-1 = 14 a(5) = 3a(4)-1 = 42-1 = 41

algebra
The number of customers visiting a local business is 48,961 and has been continuously declining at a rate of 2.5% each year. What is the approximate number of customers in 13 years. My answer is 35,230

algebra
Thank you

algebra
The population for a city is 39,194 and grows continuously at a rate of 6.9% each year. What is the approximate population in 17 years? My answer is 121,854

algebra
disregard I posted correctly in a new one

algebra
The population for a city is 39,194 and grows continuously at a rate of 6.9% each year. What is the approximate population in 17 years? My answer is 35,230

algebra
thank you

algebra
well, the amounts added are 8,11,14 They differ by 3, so it will look like a(n) = a(n-1) + 3n + ? 3n looks like 3,6,9, so we have a(n) = a(n-1) + 3(n-1)+5 = a(n-1)+(3n+2) so you are correct

algebra
an=an-1+3n an=an-1+(n+2) an=an-1+3(n+2) an=an-1+(3n+2) I thought it was the last one but am not sure and am trying to help my grandson.

algebra
A rare bacterial culture is being grown in a lab. As the days progress, the cells multiply and grow. After 1 day, there is only 1 cell. After 2 days, there are 9 cells. After 3 days, there are 20 cells. After 4 days, there are 34 cells. Which recursive equation represents the ...

Math
50?3/2-20?3/3-25?3/3 50?3/2-45?3/3 ?3(50/2-45/3) ?3(25-15) 10?3

Finance
Norris currently has an account balance of \$3,703.05. He opened the account 25 years ago with a deposit of \$1,725.95. If the interest compounds monthly, what is the interest rate on the account? My answer is 3.1%

Math
yes

Math
no, 1.0 is 10 times as much as 0.1 (which is 1/10) In decreasing order, you have ... 10.0 1.0 0.1 0.01 ... Moving the decimal point to the left is the same as dividing by 10.

math
a sec? + b tan? = c p sec? + q sec? = r I suspect a typo. Is that what you meant? That means that sec? = r/(p+q)

Physics
check out your formula relating amplitude and intensity. Then replace the amplitude with 4 times its value. See how much the intensity has grown.

calc 3
the slope at (4,16) is 8. So, the tangent vector is i + 8j The unit vector is just that, divided by the length: ?65

Math
the area is 72037.35/1.35 = 53361 m^2 so, the side length is 231 m Now just calculate the perimeter, and you can find the cost.

Math
he started with 13/13 5+4+2 = 11 so, what do you think?

Math (Pre cal)
another idea might be composition. (f?g)(x) = f(g) = g^2+3g-1 = (x^3+4x^2+1)^2+3(x^3+4x^2+1)-1 = x^6+8x^5+16x^4+5x^3+20x^2+3 (g?f)(x) = g(f) = f^3+4f^2+1 = (x^2+3x-1)^3+4(x^2+3x-1)^2+1 = x^6+9x^5+28x^4+33x^3+4x^2-15x+4

Math (Pre cal)
do what?

math - eh?
no idea what x and y have to do with the given data.

maths
clear the fraction, and you have x+y+z = 3*44 = 132 Now, since y=2x=3z, 2x=3z, and x = 3z/2 Now just add them up and you have 3z/2 + 3z + z = 132 11z/2 = 132 z = 132 * 2/11 = 24

maths
If the three numbers are x,y,z, then we know that y = 2x y = 3z (x+y+z)/3 = 44 Now just find z.

math
multiply the exponents for example, (2^3)^5 = 2^(3*5) = 2^15 why? 2^3 = 2*2*2 (2^3)^5 = 2*2*2 * 2*2*2 * 2*2*2 * 2*2*2 * 2*2*2 ^ is just shorthand for ***... Just as * is shorthand for +++... 2*3*4 = 2+2+2 + 2+2+2 + 2+2+2 + 2+2+2

Mathemetics
10250 * 0.85^9

math
(3x^2-4xy+y^2)/(9x^2-y^2) That is not an equation (there is no = sign). It is just an expression. So, let's see what we have after we factor things a bit: (3x-y)(x-y) / (3x-y)(3x+y) (x-y)/(3x+y)

Maths
Let x = # 25 coins y = # 50 coins Then we are told that x = 3y 25x+50y = 5000 now just solve for x and y.

Maths
assuming base a, log36 = log(4*9) = log4 + log9 Now, since 9 = 4^1.585 log36 = 2*1.585 + 1.585 = 4.755 Interesting, isn't it, that log_a(4) = log_4(9) ??

Marh
147.3 = 147 3/10 = 1473/10

Math
Surely you mean "arithmetic progression" not "appointment"! a+5d = 37 6/2 (2a+5d) = 147 You want 15/2 (2a+14d) so solve for a and d and plug 'em in.

Maths
a = d+4 d = k/2, so k = 2d a+d+k = 36 d+4 + d + 2d = 36 now it's easy to find d, and then a and k.

MATH
draw a velocity diagram, and you can see that the resultant speed is ?(15^2+8^2) = 17 km/hr

Math
(v+6)^2-40 = 0 (v+6)^2 = 40 v+6 = ±?40 v = -6±?40 or, v = -6±2?10

calculus II
find t such that 100-5t = 10+4t

algebra
maybe you mean cos x = -1/2 Since cos? = x/r, and ? is in QIII y = -?3 sin? = y/r = -?3/2 tan? = y/x = ?3 cot? = x/y = 1/?3 sec? = r/x = -2 csc? = r/y = -2/?3

Math
Again with the cryptic questions regarding an unseen diagram. How about this... It appears that point U is at the center. Starting with point O, name the other points, in clockwise order around U. If there are polygons formed by some of the points, name their vertices in ...

Math
Yes, but the information is related to a diagram. The position of the points makes their relationship clear to you, but not to us. Lines UT and UP are perpendicular, and point N is between T and P, and inside angle TUP. But I cannot see where points O and R lie in relation to ...

algebra -- oops
Hmmm. However did I come up with 54? weird... Anyway, way to watch.

algebra
as usual, the area is length * width: 24(-2n+17) = -48n+54

Calculus
this is the same as the question of the tangent line, just stated differently. Reflections have the same angle to the normal.

Calculus
you can start here. Other proofs are also given by google https://math.stackexchange.com/questions/214057/proving-a-property-of-an-ellipse-and-a-tangent-line-of-the-ellipse

geometry
Think about it. If the polygon has n vertices, how many lines can be drawn from one of them to each of the others?

Math
35+25 = 60% so, 40% are general .40x = 250 x = ?

algebra
if a*b = a/b then b^2 = 1 If b=1, then a+b = a*b is never true If b = -1, then a-1 = -a a = 1/2

Math
just replace each 1 with any other number. 2:2 etc.

math
?(35^2 + 12^2) = ?

Math
.021 = 21/1000 .845 = 845/1000 so, what do you think?

Math
3(n+3)-2n

Math
It seems that point B is irrelevant. <AOC = 90 <AOD = 135 So, <COD = 45 As for finding x, it seems that <COB + <BOA = 90 3x-7 + (-2x+4) = 90 x-3 = 90 x = 93 But that makes no sense, since then <BOA is negative. If you lay out the diagram, with point A at the ...

Math
not likely. How did you figure it? If x=138, -2x+4 = -272 not likely one of the angles

Math
Huh? If the points A,B,C,D are in sequence, then since <AOC = 90, <DOC = 135-90 = 45 If the angles are in some other order, then you may have to find x first.

Math
15+4x+8 = 83 4x = 60 x = 15

science
Assuming that the bowl is a perfect insulator, and does not absorb any of the energies involved, then only A is false. No energy is destroyed. C and D certainly will occur. If the bowl interacts with the pie and ice cream, then depending on its temperature, it might affect ...

Thank you Could it be written as a(n)=a(n-1)+2^n-3

a(1) = 0 a(n+1) = a(n)+(2n-1) or, a(n) = (n-1)^2

A playground is being designed where children can interact with their friends in certain combinations. If there is 1 child, there can be 0 interactions. If there are 2 children, there can be 1 interactions. If there are 3 children, there can be 4 interactions. If there are 4 ...

MATH
check out associative

math
thnx its 45

math
use compatable numbers and then divide 448/8

math
You say the pool is 12m wide, but both ends are only 10m wide. I'll assume that's a typo, and the pool is 10m wide. The side view is a trapezoid with bases of 1.3 and 3, and an altitude of 40. So the volume of the pool is (1.3+3)/2 * 40 * 10 = 860 m^3 The volume of ...

math helllppppp
D is correct.

Precalculus
yeah, you already said that. But what does tangent to y=x+20(11,9) mean?

Precalculus - eh?
hmmm. I see a couple of straight lines, and what may be a point. I fail to see any circles or other curves involved. Maybe a little more explanation will help. Do you want the equation of a circle whose center is on y=1/3x+6, and is tangent to y=x+20? If so, where does (11,9) ...

Math
You have a sum of an arithmetic progression, where the common difference is 7. 50/2 (2a+49*7) = 12075 a = 70 70+49*7 = 413 So, numbers range from 70 to 413

Maths
3c = h c+h = 1600 now just find c and h.

Maths
the consecutive numbers are x, x+1, x+2 you are told that x + x+1 = 39 + x+2 solve for x and you're almost done.

math
there are six faces on the box. two of length x breadth two of length x height two of breadth x height so, just use your dimensions and crank out the products.

Physics
I agree except for B. People are mammals, which have internal body heat regulation. They maintain roughly the same temperature regardless of environment. Reptiles and other cold-blooded animals cannot do this, and their internal temperature is much more greatly affected by ...

Algebra
notice that 2 is a factor of each term. So, factor it out. 2(x+y)

math
age now: x age in 5 years: x+5 age 5 years ago: x-5 so, write the words in math x+5 = 2(x-5)^2 now just solve for x. Since you have a quadratic function, you will get two answers. Only one answer will make sense.

Calculus
by x=1,2 do you mean 1.2 or 6/5? Anyway, the volume from x=a to ? is ?[a,?] ?y^2 dx = ?[a,?] ?/x^2 dx = ?/a

Calculus
do you want the arc length (above and below the x-axis), or the surface when the arc (above or below the axis) is rotated about the x-axis?