Friday
April 18, 2014

Posts by STEVE


Total # Posts: 21,739

Geometry
pick the set with perimeter=12 since 12*3=36

Geometry
um, try 4/20

Geometry
ACFGH

trigonomentry
No, Ada travels from A on a heading of 60˚ because B lies on a bearing of 60˚ from A. Then she apparently gets lost . . .

mat 116
I'd say where the graphs intersect.

mat 116
if you rearrange into the same format, you have 2x+4y = -1 6x+12y = -3 If you multiply the 1st by 3, you see that it is the same as the 2nd. So, they are really the same line, and there are infinitely many solutions. That is, every point on the 1st line is also on the 2nd line...

Math
162 = 18r^2 r = 3 18 = 9a, so a = 2 S7 = 2(1-3^7)/(1-3) = 2186 check: 2+6+18+54+162+486+1458 = 2186

math
is there a problem with finding 1/4 or 1/8 of the values shown? 16/4 = 4 16/8 = 2 and so on

Science - ?
Hmmm. I get d3 = 6*4 + 1/2 (-6/4)*4^2 since v goes from 6 to 0 in 4 seconds. bob's the physicist, but ...

science
h = 15.8 + (25.2 sin 32.7°)t - 4.9t^2 = 15.8 + 13.61t - 4.9t^2 I get max height = 25.25 at t=1.388, which is as you say, 9.46m above the roof. h=0 when t=3.66 v = 13.61 - 9.8t = -22.26 when h=0

Math
x + x/(3/2) + x+2 = 98 x = 36 so, the sides are 36,24,38

math
under addition, each element x has an inverse such that x + x^-1 = 0 (the additive identity) under multiplication each element has an inverse such that x * x^-1 = 1, except zero. both operations are associative and commutative, which fill out the necessary conditions.

maths
depends on the length, unless the width is the diameter of a circular pool, in which case you have 3/4 * pi * 100^2 * 48 cm^3 divide that by 1000 to get liters

MATH
If you mean 16^2 √24 / 6√56 then that is 128/√21 I suspect that is not what you meant, so try again using √ instead of the character from your other application.

MATH
7√2 * 3√9 = 7√2 * 3*3 = 63√2

Algebra
just substitute in for x f(t-2) = 5+6(t-2)-(t-2)^2 = -t^2 + 10t - 11 do the others the same way.

Math
p -> q q -> r p -> r valid

math
cost: 40*3.20 = 128.00 after spoilage there are only 32 dinners to sell Now, if the 32 dinners are supposed to cover the entire cost + 80% markup, that would mean they must sell at a price p such that 32p = 1.80*128 p = 7.20 So, the $1 discount is a 13.9% discount off the mark...

Math
181.278 and 418.722 not sure how you want to round them

algebra
c'mon, snow -- take a look. There's a 1.75 fee just to start with. After that, each ticket costs 25, so for t tickets, that would be 24t. $25t+1.75 fits the conditions plug in 6 for t and pick the final answer.

algebra
If not, the only value that does not fit with integer x is -21

Math
v = 4/3 pi r^3 a = 4pi r^2 dv/dt = 4pi r^2 dr/dt da/dt = 8pi r dr/dt when v=500pi/3, r=5 5 = 100pi dr/dt dr/dt = 1/(20pi) da/dt = 8pi r dr/dt = 8pi*5/(20pi) = 2

math
D

algebra
looks like D to me

Math
aha. As before, you divided by 100 twice, not just once.

Math
18% is about 1/5 1/5 of 880 is 176. How do you come up with such a small value?

math
I don't know what you are using, but the answer is .62 * 146 = 90.52 You have some serious problems with your decimal points. 62% is 0.62, You got 0.62%, or 1/100 of the real answer. You did the conversion twice. divide by 100 to convert 62% to 0.62, but don't divide b...

math
try a sanity check. 62% is about 2/3 so, you want a number less than 146. How ever did you get such a huge answer?

physics
In fact, I get that a Vi = 67 m/s is required if the ball is to be able to go over the bar at its max height, and more than that if we expect to have two values for θ.

physics
as you know, the height of the ball at distance x is y(x) = tanθ x - 4.9/(v cosθ)^2 x^2 Using our data, we need to solve 42.2 tanθ - 4.9/(27.4 cosθ)^2 (42.2^2) = 3.44 42.2 tanθ - 4.9/(27.4^2 (1+tan^2θ))(42.2^2) = 3.44 I get tanθ = 1/3, but I ...

geometry
Oh, my. I'm not asking you what it said; I'm asking whether you cannot figure out how far away from the y-axis the point (2,5) is. draw the x- and y- axes, and plot the point (2,5). If you can do that, you can just look at the graph paper and see how far the point is f...

geometry
How far is (2,5) from the y-axis? K is the same distance away on the other side.

Geometry
you can see why Reiny's asking his question. If the base of the lighthouse is at sea level, then the man's eyes are at the same height as the top of the lighthouse, and the angle of elevation will be zero. So, if the base of the lighthouse is at height h, then the top ...

Math
If the 3 products are made in quantities x,y,z, then maximize p=35x+60y subject to 2x+y <= 70 x+y <= 40 x+2y <= 90 maximum profit at (0,40) = 2400 good tool at http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html set the x- and y- ranges at 0-50 and it will show a d...

math
c * 1.30 * 0.90 = 259.92 c = $222.15

Trigonometry - eh?
the first part is unclear. What do you mean by "encounter"? it's just an expression like any other; it has no "answer". What is the LCD of x^2 and x^3? Hard to say, since there are no fractions involved. The GCF is just x^2; the LCM is x^3.

Maths
8 * 2 5/6 * 6 = $136

math
if the front of the log is x feet from the bridge, and y is the length of the log, then 30/x = tan 16.7° 30/(x+y) = tan 14° eliminate x: 30/tan 16.7° = 30/tan 14° - y Now solve for y: y = 30(cot 14° - cot 16.7°)

Geometry equation of circles
the two lines are 5 apart, so the radius is 5/2, with the center at (7/2,k) so (x - 7/2)^ + (y-k)^2 = (5/2)^2 The point (2,2) is on the line, so (2 - 7/2)^2 + (2-k)^2 = (5/2)^2 k = 0 or 4 (x - 7/2)^2 + (y-4)^2 = (5/2)^2 (x - 7/2)^2 + y^2 = (5/2)^2 So, the question is misleadin...

College Algebra
Looks good to me.

Algebra - Functions
all polynomials have domain of (-∞,+∞) √u has domain u >= 0 rational functions have domains which exclude where the denominator is zero. Keeping that in mind, I'll do (b), and the rest should be easy. √(x+3) needs x+3 >= 0, or x >= -3 the d...

Maths - oooops
Double the 14, not the answer: (1100*100)/(28pi) = 1250.5

Maths - oops
oops. double that. I took c=pi*r, not pi*d.

Maths
(1100*100)/(14pi) = 2501

Algebra 1 (Reiny)
2r(r-3) - 4(r-3) ...

Algebra
the total will be 10000*e^(8*.054) = 15,403.35

Trig
or, if you divide top and bottom by cosØ you have (secØ-tanØ)/(secØ+tanØ) now multiply top and bottom by (secØ-tanØ) and you have (secØ-tanØ)^2 / (sec^2Ø-tan^2Ø) = sec^2Ø - 2secØtan&Osla...

Pre-Calculus
y = v sinθ t - 16t^2 x = v cosθ t You have θ and v, so plug those in and solve for x when y=10 to get the max goal distance. or, y = x tanθ - 16/(v cosθ)^2 x^2

Pre-Calculus
Reiny gave you good polar coordinates, but if all you want is parametric equations, try x = t/3 y = 1 + t/2 or x = -(2+t)/3 y = -2t

Calculus Please help!
the linearization is just finding a straight line that is close to the curve at the given point. That is just the tangent line. So, since when y = √(1+2x), y' = 1/√(1+2x) y(0) = 1 y'(0) = 1 and the point-slope form for the line is y-1 = 1(x-0) y = x+1 A=1 a...

Math
Assuming no overhang at the eaves, the length of the roof is 50 ft and the width on each side is w^2 = 15^2 + 6.5^2 w = 16.35 So, the area is 2 * 50 * 16.35 = 1635 ft^2

math(algebra)
(C)

MATH
4^4 * 4^2 = 4^(4+2) = 4^6

STEVE!! CAN YOU PLEASE TELL ME HOW U GOT CHOICE D?
as you know a^2+b^2=c^2, so if a=b, c = √(2a^2) = a√2 In this case, a=4

math(algebra)
the distance is the length of the hypotenuse of the right triangle whose legs are 4 and 4 Looks like (D)

Calc Help Please
from the left, the first definition shows the limit is -13/3 from the right, the second definition applies, and the limit = 0 Naturally, f is not continuous where 3x^2-15=0, or x = ±√5 Also, at x = -2, since the limit does not equal the definition. Also at x=2, si...

Math 30-2
7C4 + 7C5 + 7C6 + 7C7 = 64 since n ∑ nCk = 2^n k=0

Calculus Please help!
As usual, draw a diagram. The distance between the ships at time t hours is d^2 = (50+18t)^2 + 23t^2 At 3 pm, t=3, so d = √(104^2+69^2) = 124.8 2d dd/dt = 36(50+18t)+46t so, dd/dt = 15.6 knots

Calculus Please help!
so, did you draw a diagram as suggested? a = 1/2 bh so, b = 2a/h da/dt = 1/2 (db/dt * h + b * dh/dt) Now just plug in your values: 3500 = 1/2 (db/dt * 7000 + 2*87/7 * 2500) db/dt = -7.88

Calc help
is there something wrong with the solution I gave at http://www.jiskha.com/display.cgi?id=1393553002 ?

math
3√(3/8) = 3(√(1/4 * 3/2) = 3 * 1/2 √(3/2) = 3/2 √(3/2) Not sure that's any simpler, but the radicand doesn't have any factors which are perfect squares. It'd also be √(27/8) Now, if you meant ∛(3/8), that would be ∛(3 * 1/8...

math
3x^2 √(5x) * 3√(3x^3) = 9x^2 √(5x*3x^3) = 9x^2 √(15x^4) = 9√15 x^4

Math
cost: 40*3.20 = 128.00 after spoilage there are only 32 dinners to sell Now, if the 32 dinners are supposed to cover the entire cost + 80% markup, that would mean they must sell at a price p such that 32p = 1.80*128 p = 7.20 So, the $1 discount is a 13.9% discount off the mark...

Algebra 2
#1 2x(x-12) = -40 x(x-12) + 20 = 0 x^2-12x+20 = 0 (x-2)(x-10) = 0 #2 3x^2 + 2x = 12 - 7x 3x^2 + 9x - 12 = 0 x^2+3x-4 = 0 (x+4)(x-1) = 0 #3 8√-63 = 8√63 i #4 |7+24i| = √(7^2 + 24^2) = 25 #5 (4-7i)(2+3i) = 8 - 14i + 12i - 21i^2 = 29-2i

operating system
DOS is a text-based interface. Commands are typed in. Unless you know the command name and the path to its location, you are SOL. Windows is a GUI (Graphical User Interface) where you move the cursor to icons and click to perform actions.

math
( tanx + cotx )² = tan^2 + 2 + cot^2 = sec^2 - 1 + 2 + csc^2 - 1 Now it should be easy.

calculus
the graph can be seen here: http://www.wolframalpha.com/input/?i=plot+y%3D|x^2+%2Bx-2|+for+-4+%3C%3D+x+%3C%3D+3 That should make it easy to answer the other questions. If not, come on back and show where you get stuck.

Algebra
Not quite: A: x-coordinate of the vertex, also of the axis of symmetry B: not a quadratic at all; just a line C: the discriminant D: likely the parent equation E: quadratic formula. Note how the roots are equally spaced around x = -b/2a

Math
h(t) gives the height for any value of t. For this problem, wherever you see a t, substitute 40: h(40) = 81.69 + 2.39*40

Algebra
first, it's "whether" not "weather". Look at the coefficient of x^2. Since x^2 is always positive, the parabola grows upward if the coefficient is positive, and downward if it is negative. The easy way to find the vertex and axis is to complete the squa...

Math
in the two hours between the buses, the first bus has traveled 60 miles. So, the other bus must make up 60 miles at 50 mi/hr, which will take 60/50 hours. Add that time to the bus's departure time.

Algebra help ASAP please
I'm sure you can factor x^2-x-2, no? This is the same things (2x+1)(x-1) Not quite sure what it has to do with #1, though #2 ok #3. Since the top and bottom are of equal degree, there should be no unbalanced x's between the top and bottom (6x^2+4x)/(2x^2+4x) = 2x(3x+2)...

Math
9(1.06^5x + 1) = 15 (1.06^5x + 1) = 15/9 1.06^5x = 2/3 5x log 1.06 = log (2/3) x = log(2/3) / (5log 1.06)

Calculus
by the time you get to calculus, you certainly should know how to plug in a value and evaluate a function! Where do you get stuck? (a) q(5) = 10300*e^(-0.34*5) = 1882 (b) as you know, if y = e^u y' = e^u u' And, as you know, the derivative is the rate of change. So, q&...

math
the amount of acid in each part must total the acid in the mixture, so .05x + .09(40-x) = .06(40) Now just solve for x, the amount of 5% acid.

Algebra 2
the max or min of a quadratic is at the vertex of the parabola. I expect you can determine whether the vertex is a max or a min. So, since the vertex is at x = -b/2a, (2) -3x^2-6x-9 the vertex is at x = -6/(2*-3) = 1 y(1) = -18, so the vertex is at (1,-18) (3) the vertex of y-...

Math
the midpoint is halfway from one to the other. That means its coordinates are the average of the x- and y- values of the two points: (-1,-4) Note that -1 is halfway from 2 to -4 (3 away from both ends)

math (algebra honors)
(x+2)^3 - x^3 = 386 6x^2 + 12x + 8 = 386 x^2 + 2x - 63 (x+9)(x-7) the shorter side is 7 check: 9^3-7^3 = 729-343 = 386

algebra word problem
when the cyclist starts, the runner is 5 miles ahead. So, he needs to make up 5 miles at 13 mi/hr, which takes 5/13 hours.

Geometry
If all we have is one side and one angle, there's no way to determine any of the missing info. Now, if we're working with a right triangle, then the side opposite the angle is x/59 = tan 35° But since this is geometry, not trig, I don't know whether that's ...

Quick math help
Looks like an exercise set using factoring by grouping. 4n^3+4n^2-16n-16 4(n^3+n^2-4n-4) 4(n^3-4n + n^2-4) 4(n(n^2-4) + (n^2-4)) 4(n+1)(n^2-4) 4(n+1)(n-2)(n+2) 9k^3-15k^2-3k+5 3k(k^2-1) - 5(k^2-1) (3x-5)(k-1)(k+1) 60m^3+48m^2-20m-16 4(15m^3 + 12m^2 - 5m - 4) 4(5m(3m^2-1) + 4(3...

Calc Help :(((((
As x->∞, only the highest powers are relevant, so we wind up with the limit of 7x^(5/3) / -2x^(8/5) = -7/2 x^1/15 -> -∞ Or, you can divide top and bottom by x^(5/3) and then throw away all the fractions with x in the bottom

math algebra
the distance between the trains grows at 115+95 = 210 mi/hr So, it will take 504/210 hours to get 504 miles apart.

Algebra 1 (Reiny)
It's not clear just what you mean by "the greatest number" If you put 72 of each berry into each tart, you can make only 1. If you put 36 of each kind of berry into each tart, then you can make only 2 tarts, with 36 blueberries left over. If you put 3 raspberries...

Chemistry
Use standard enthalpies of formation to determine ΔHorxnfor: 3NO2(g) + H2O(l) → 2HNO3(aq) + NO(g) -133.5 = Delta H Find the change in internal energy for this reactioion.. ???? In KJ

Algebra 1
pi * 6^2 * 5 ft^3

Algebra
If the first digit is t (for tens) and the 2nd digit is u (for units), then u = 5t+2 5t = u+3 Sorry, no solution. Care to rethink it?

Algebra 1
87+3(x-1)

Chemistry
#1 - no way to know, without some information about the pressure. #2,3 just remember that mass = density * volume Look up the density of ice and aluminum, and you're almost done.

Calculus Help
get a better table

Algebra
the powers are 0,5,6,10

Math
5n+25q = 620 5q+25n = 620+320 now just solve for q.

calculus
Or, post your results and we can verify them.

calculus
assuming you just need to confirm your answers, I'll say none |x+.5|>1.5 monotone over any interval not including the x-values -2,-.5,1 up: x<-2 and x>1 down: -2<x<1 no inflection http://www.wolframalpha.com/input/?i=|x^2+%2Bx-2|

Algebra
ummm, that would be x^2 + x^2 = 2x^2 just as 4x+7x = 11x and 4+10 = 14 just collect all the terms with the same power x^2 means 1x^2, so x^2+x^2 = 1x^2 + 1x^2 = 2x^2

math
However, they are asking for the smallest square greater than 64, which is 81. Note that -8^2 = -(8^2) = -64 (-8)^2 = +64

trig
if the building is at distance d from the tree of height h, draw a diagram to see that (150-h)/d = tan 50° h/d = tan 22° plugging in the numbers, h+1.19d = 150 h = 0.40d So, we have h = 94.3 d = 37.7

math
If we convert the dimensions to inches, then the kitchen is 1224 by 216 inches. 1224/28 = 43.7 216/28 = 7.7 So, assuming no fractional tiles are to be reused, we need 44*8=352 tiles. The only weird thing about this problem is the idea of a kitchen 102 feet long!!! Is there a t...

math
they are not integers they may be negative

Algebra 2 Homework
#1 x^2+10x+9 = x^2+10x+25 + 8-25 = (x+5)^2 - 16 Since the vertex is at (-5,-16), the axis of symmetry is at x = -5 Or, you can consider that the roots are at -9 and -1, and the axis is midway between the roots, or at x = -5. #2 3x^2+12x+16 = 3(x^2+4x) + 16 = 3(x^2+4x+4) + 16-3...

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