Friday
April 29, 2016

Posts by Steve

Total # Posts: 40,013

math
"of" usually means "times" so .05*200 = ?
March 1, 2016

Calculus Related Rates
the distance z at height x is z^2 = 50^2 + x^2 so, 2z dz/dt = 2x dx/dt find z when x = 5*20=100, and plug and chug. tanθ = x/50 sec^2 θ dθ/dt = 1/50 dx/dt
March 1, 2016

MATH
just plug and chug. f(x^2) = 3x^2-2 f(f(x)) = 3f(x)-2 = 3(3x-2)-2 = 9x-8 the others are trivial.
March 1, 2016

math
you can play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html It's a handy tool.
March 1, 2016

precalculus
we want the ship's heading, not bearing. using the law of cosines, 60^2 + 139^2 - 2(60)(139)cosθ = 80^2 now just find θ (that is the direction relative to due east, not the ship's heading)
March 1, 2016

Geometry
the special characters are mangled in my browser. Better describe things differently. Try using <B for "angle B" and forget the overlines; just name the line segments.
March 1, 2016

Math
starting at T, we need after h hours, T-3h >= -78
March 1, 2016

Algebra A
clearly, if 2nd has sides half as long, it has twice as many sides.
March 1, 2016

Linux
you must have some ideas. Is this a bash script? I assume you know how to do SQL queries.
March 1, 2016

Math
well, just plug in your values: 2.5a - 3b(-4.1 + a(-3.3b - b) - b) + a 2.5(-0.5) - 3(2.5)(-4.1 + (-0.5)(-3.3(2.5) - (2.5)) - (2.5)) + (-0.5) Work through step by step, and you should come up with 7.4375
March 1, 2016

Maths
if 100g = 5x, x=20, meaning she uses 160g of flakes. Any more than that, and she'd need more than 100g of fruit. 84g = 7x; x=12 so, she needs 12*3=36g of raisins. Using any more than 36g means x>12, and she'd need more than 84g of nuts.
March 1, 2016

Math
(2k)(2k+2) = 2k + 2k+2 + 14 I used 2k, because we need to be sure that the numbers are even. We might have used x(x+2) = x + x+2 + 14 but it might turn out that x is odd.
March 1, 2016

Pre- Algebra
assuming no overlap, 218 of 490 students like the program. So, the angle is 218/490 * 360°
March 1, 2016

Ms. Sue? Steve? Anyone?
geez, impatient much? see your post of 5 seconds ago...
March 1, 2016

MATH
with base radius r, the total area is πr^2 + πrs where s^2 = r^2+h^2 Just plug in your numbers
March 1, 2016

Math
just put the words into math: x+y=15 4x = 2y-60 Now just solve the system for y.
March 1, 2016

Math
with constant k, the relation is y = kx So, plug in your constant.
March 1, 2016

Algebra
#6 ok #7 ?!?!!? y = 4x and y + x = 5 4x+x = 5 x=1 ... #8 ?!?!?!? NO SOLUTION They never cross. Parallel
March 1, 2016

Algebra
.6/50 + .4/x = 1/45 x = 39.13 check. For ease of reading, say the distance is 100 miles 60% is 60 mi 60mi @ 50 mi/hr = 1.2 hr 40mi @ 39.13 mi/hr = 1.022 hr 100mi @ 45mi/hr = 2.222 hr = 1.2 + 1.022
March 1, 2016

Exponents
take a look at your previous post. Reduce the left hand side to an expression of the form x^f(p) y^g(q) = xy Then just solve f(p) = 1 g(q) = 1
March 1, 2016

Gr 12 Math
Gr 12?? This is grade 1!
March 1, 2016

Exponents
Your notation is unclear. It appears that you want to say (x^−2/x^1)^p · (y^q/x)^2=xy (x^-3)^p (y^q/x)^2 = xy x^-(3p+2) y^(2q) = xy equating powers, we have 3p+2 = -1 p = -1 2q = 1 q = 1/2
March 1, 2016

Math
that's better
March 1, 2016

Math
try again. The prism has six.
March 1, 2016

Math
wow - this is a bit different from the usual ones. Set A at (0,0). Then B is at (80,0). Label the two aircraft C and D. We want to find CD. AC has slope tan60° = 1.732 BC has slope tan104° = -4.011 AD has slope tan125° = -1.428 BD has slope tan157° = 0.424 So, ...
March 1, 2016

Algebra
notice that y increases by 4 for every 1 increase in x. So, the function will look like y = 4x + ... Since 4*2=8, and y(2) = 23, y = 4x+15 Since the domain is x>=2, you could rewrite that as y = 4(x-2) + 23
March 1, 2016

Calculus
see the related questions below
March 1, 2016

Calculus
a = πr^2 da/dt = 2πr dr/dt
March 1, 2016

Calculus
see related questions below
March 1, 2016

calculus
draw a diagram. I assume he is running from 2nd base to 3rd base, other wise it is trivial. The distance z when he is x ft from 3rd base is z^2 = x^2 + 90^2 2z dz/dt = 2x dx/dt
March 1, 2016

Maths
r•a/|a|
March 1, 2016

Maths
they appear correct
March 1, 2016

Calculus, Math word problems.
x^2h=500, so h = 500/x^2 v = x^2h A = x^2 + 4xh = x^2 + 2000/x dA/dx = 2x - 2000/x^2 = 2x(x^2-1000)/x^2
March 1, 2016

algebra
p(t) = ce^(kt) p(0) = 29, so c=29 p(12) = 38 29e^(12k) = 38 Now just solve for k
February 29, 2016

Math
can't do it here. Look at number line examples. Draw the number line. Mark the point at -1/4 with a filled dot. Shade everything to the right of the dot.
February 29, 2016

Math
well, 4 of the 5 spaces are NOT 4.
February 29, 2016

Math
3(x+6) + 2x
February 29, 2016

Calculus
v = x^2 h now use the product rule and chain rule: dv/dt = 2xh dx/dt + x^2 dh/dt Now just plug in your numbers
February 29, 2016

calc
well, the error is the approximate value minus the real value.
February 29, 2016

Calculus help, very confused!!
(a) well, you know critical numbers are where f'(x) is zero or undefined. we can factor out the K and ignore it, since it is just a scale factor. Using f(x) = (1+c^2x^3)/(1+x)^3 f' = (3c^2x^2)(1+x)^3 - (1+c^2x^3)(3)(1+x)^2...
February 29, 2016

Trig
s = rθ just plug in your numbers (in radians)
February 29, 2016

math
just recall that cos4x = 2cos^2(2x)-1 cos2x = 2cos^2(x)-1 expand and it all works out.
February 29, 2016

math
well, cos2x = 2cos^2x-1 cos4x = 2cos^2(2x)-1 = 2(2cos^2x-1)^2-1 now expand all that out separate out the cos^4x
February 29, 2016

math
#1 ok #2 ok #3 (4p-2)(p-4) = 4p^2-18p+8 where did pi and x come from?? #4 ahh. maybe here #5 6x^3+14x-5x-3 you can always type in your expressions at wolframalpha.com to verify your results. For example, http://www.wolframalpha.com/input/?i=%282x^2%2B4x-3%29%283x%2B1%29
February 29, 2016

Geometry
what? bh/2 is the area of a triangle. You need to get the distance d using 173/d = sin40°
February 29, 2016

Algebra
well, to start, x=0. What is 2^0 ?
February 29, 2016

Physics
generally, yes, though in this problem, all you wanted was the time period, in seconds.
February 29, 2016

Physics
exactly the reverse period = time/rev = 68/16 always watch the units 16/68 is how much of a revolution it makes in 1 second.
February 29, 2016

physics
since speed at the top is all horizontal, we know that 35.5 cosθ = 34 Now you can figure the vertical speed at takeoff, so use what you know about max height given initial vertical speed.
February 29, 2016

physics
KE = 1/2 mv^2, so just plug in your numbers. Now, if we have 2v instead of v, that gives us 1/2 m(2v)^2 = 1/2 m*4v^2 = 4(1/2 mv^2) since KE varies as v^2, 2v gives 2^2 times the energy.
February 29, 2016

Math
you cannot divide by zero. so, when x=4, 1/(x-4) is undefined. There is a vertical asymptote there. For the horizontal asymptote, you need to see what y does when x gets huge. See the graph at http://www.wolframalpha.com/input/?i=1%2F%28x-4%29%2B3 use google to find more ...
February 29, 2016

Math
did this for you three days ago. http://www.jiskha.com/display.cgi?id=1456531698 still unclear?
February 29, 2016

Math
x*e^(.03*6) = 4000
February 29, 2016

PT1420
0 1 2 3 4 5
February 29, 2016

Calculus/Vectors
Assuming that the long side is parallel to the ground, the length of the shade is clearly still 2m. As for the width, think about it. If the shade were laid flat, the width would be 1.5m. If the shade were standing up straight, the shadow would be just a line. So, what trig ...
February 29, 2016

Math
bottom: 9x10 two sides: 8x12 two sides: 10x12
February 29, 2016

science
We know the mass of H is 1, so N:H = 14:3 ammonia is HN3
February 29, 2016

math
clearly the 1st choice has a 4/5 chance of being a minimum. If chosen, there are only 3 left, so the probability of the 2nd draw is 3/4 So, P(min,min) = 4/5 * 3/4 = 3/5
February 29, 2016

geometry
Draw a diagram. Clearly, CD^2 + 8^2 = 12^2 Now you have CD, and thus BD=10-DC AB^2 = BD^2 + 8^2 Now you have AB BE^2 + EC^2 = 10^2 BE^2 + (12-EC)^2 = AB^2 Now just solve for BE
February 29, 2016

math
If there are n days, then (850)(.025/365)(n) unless you use a 360-day year for calculations
February 29, 2016

Trigonometry
You got your formula a bit garbled. cos(A-B) = cosAcosB + sinAsinB Recalling some well-known values, that is cosθ cosπ + sinθ sinπ = cosθ(-1) + sinθ(0) = -cosθ But then, you know that from working with reference angles in the various ...
February 29, 2016

Triginometry
1'5" = 17" so, tanθ = 36/17
February 29, 2016

alg 2
x^2 = e^x - 2.4 Got to solve that graphically. Do it carefully and you will find that x ≈ 1.6 http://www.wolframalpha.com/input/?i=x^2+%3D+e^x+-+2.4
February 29, 2016

Math
well, what are the integer divisors of 20? That will give the number of trees across and down. But that is not the answer to the question.
February 29, 2016

math
8+x = 100/4 8+x = 25 ...
February 29, 2016

Mathematics
m = 4s m-7 = s + 11 This is interpreting the 2nd condition as 7 years ago the man was 11 years older than his son is now
February 29, 2016

Algebra
not 20x15, since the length is 23!
February 29, 2016

Algebra
w(w+23) = 420
February 29, 2016

science
well, that would be 1 mole, right?
February 29, 2016

Math
You have very strange notation. I assume you mean limit as x -> π/2 of tan^2 √(2sin^2(x) + 3sinx + 4 - sin^2(x) + 6sinx + 2) Clearly there is something wrong here. Try clearing it up, ok? If I got it right, we have tan^2(√(sin^2(x) - 3sinx + 2)) = tan^2(&#...
February 29, 2016

math
Not clear how many years. You say one year, but I'm not sure. Anyway, plug in a value for n years, and solve for A. A(1+.05)^n = 5000
February 29, 2016

Math
s = a+10 18a+12s = 240
February 29, 2016

math
1600((1+.13)^3-1)
February 29, 2016

Math final exams
If you have a month to go, just review all the material you have covered. Try exercises that seem unclear, check online for help. Google is your friend. You can get examples and viewpoints different from those in your text. Make sure you know how to solve the problems, so you ...
February 29, 2016

Maths
no fig
February 28, 2016

halp
worst case, just try the possibilities. One will work. Or, using substitution, note that #3: y=x+5, so x+5 = x^2-x+2 x^2=2x-3 = 0 ... #4: y=x+2, so x+2 = x^2-2x-8 x^2-3x-10 = 0 ... Now it's just factoring.
February 28, 2016

Math
Check out Newton's law of cooling
February 28, 2016

Math
Label the vertices counterclockwise, ABCD, so that AB is the longer base, and DC the shorter base. If you draw a diagram, you will see that A,D and B,C form supplementary pairs. That is A+D = B+C = 180°
February 28, 2016

math
don't forget your Algebra I now that you're in trig: 4sin^2x+4√2 cosx-6 4(1-cos^2x)+4√2 cosx-6 4 - 4cos^2x + 4√2 cosx - 6 = 0 4cos^2x - 4√2 cosx + 2 = 0 2cos^2x - 2√2 cosx + 1 = 0 (√2 cosx - 1)^2 = 0 cosx = 1/√2 x = 2kπ &...
February 28, 2016

urgent!
ever hear of google?
February 28, 2016

Information technology
maxname="" maxsales=0 maxcomm=0 name="x" ; stop reading on a blank line while name ≠ "" {   read name,sales   comm = sales*0.05   if comm > maxcomm {     maxname=name    &...
February 28, 2016

math
well, 5*3 = 15, so ...
February 28, 2016

Calculus
surely as a calculus student, you can determine C and k: at t=0, C/(1+C) = 1/200 C = 1/199 Since you say daily volume, I assume t is in days, so at t=28, (1/199)e^28k/(1+(1/199)e^28k) = 1/100 k ≈ 0.025 = 1/40 p(t) = 1/199 e^(t/40)/(1+1/199 e^(t/40)) increasing most ...
February 28, 2016

Math
dy/dx = (dy/ds)/(dx/ds) = (-24s^2)/(18s) = -4s/3 naturally, dy/dx=0 at s = 0 see the graph http://www.wolframalpha.com/input/?i=plot+x+%3D+9s^2+-+1,++y+%3D+1+-+8s^3
February 28, 2016

Math
2.58x = 92.96
February 28, 2016

geometry
Draw a diagram. If the intersection points subtend an angle of θ, then the area of overlap is 2*(1/2)r^2(θ-sinθ) so, you have 6.17^2 (θ-sinθ) = 42.7 θ = 2 The distance between centers is then 2rcos(θ/2) = 2*6.17*cos(1) = 6.67
February 28, 2016

Algebra
If the smaller is x, the larger is x+10. So, we have 2(x+10)-x = 14
February 28, 2016

Maths
T11-T3 = 8d = (-7)-9 = -16 so, d = -2 Now you can find a, and then write the 1st 5 terms. Or, knowing d=-2, and T3=9, you can work from both sides of T3: 13 11 9 7 5
February 28, 2016

Grade 11 Functions
what you are doing wrong is ignoring the cotangent function. If you check your diagram, you will see that the height h is found using h cot17° - h cot21° = 60 h = 90.1 m
February 28, 2016

Chemistry
N2 + 3H2 = 2NH3 ever heard of google?
February 28, 2016

math
planes fly on headings, not bearings. Man, those two headings are almost the same. The distance will be very nearly 200+350. However, using the law of cosines, the distance z is z^2 = 200^2 + 350^2 - 2*200*350*cos178°
February 28, 2016

Math.
the discount is 30-22.50 = 7.50 The % discount is 7.50/30 = .25 = 25%
February 28, 2016

maths
apparently you want a = 16πr^2 can't happen But, if you meant a = 16π then you have 16π = πr^2 r^2 = 16 r = 4
February 28, 2016

Computer
LET S = (N/2)*(2*A + (N-1)*D) you don't need much of a program or flowchart to evaluate a simple expression...
February 28, 2016

Grammar
#1. Better would be He would neither show me his papers, nor tell me who he is. #2. I don't possess anything else. #3 is ok, but "every" is singular: Every man in the street stood where he was.
February 28, 2016

@Reiny - mea culpa
Ouch - I must be going Blind!
February 27, 2016

precal
diameter = 11, not radius
February 27, 2016

Calculus Pre Test Monday Part 3
s(t) = 180-5t^2 (a) avg velocity is total distance/total time. s(2) = 180-5*4 = 160 160m/2s = 80 m/s v(t) = ds/dt = -10t v(4) = -40 180-5t^2 = 0 t = 6 That is, at t=6, the height is zero -- it hit the ground. Now you just plug 6 into v(t)
February 27, 2016

Maths
y = 2cos(2x)cos(14x) use the product rule: y' = 2(-sin(2x))(2)cos(14x) + 2cos(2x)(-sin(14x))(14) and you can factor out some numbers there. The verb is differentiate, not derive. It would work the same way in general: y = 2[cos1/2(f1 - f2)x][cos1/2(f1 + f2)x] y' = 2(-...
February 27, 2016

Math
Umm, I guess that would be (2358-99)/3 right?
February 27, 2016

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