# Posts by STEVE

Total # Posts: 52,292

math test help
that covers a lot of ground. Don't expect an online course here. That's what your text was for. Any general explanations we can provide will look a lot like your text, dontcha think? Or, you can google topics of interest.

math test help
but if you have a particular problem that is vexing you, we can help get to the solution. If you haven't studied the topic by now, it may be too late...

math
The sum of their ages 2 years ago was 8*20 = 160 So, if the new child's age is x, 160 + 8*2 + x = 9*20 x = 4

math
Hmmm. I'm not sure I agree. Since A&B can fill the tank so fast, and it takes about 9 times as long to fill it with the leak, the leak must be pretty fast in relation to the fill speeds. You sure that 5 minutes is right?

math
A&B together take 1/(1/5 + 1/20) = 4 minutes to fill the tank. So, if the leak takes x minutes to empty the tank, 1/4 - 1/x = 1/(30+4) x = 68/15 = 4 8/15 minutes

calculus
use product rule

calculus
these are all just powers of x. Use the power rule: d/dx x^n = n x^(n-1)

math
If his speed was x, then since time = distance/speed, 30/15 + 16/x = 10/3

Math
If the two legs are x, then x^2/2 = 25/2 x = 5 so now you can get the hypotenuse. Or, since a = s^2/2 h = s?2 h^2 = 2s^2 = 4a h = 2?a

Maths
a little synthetic division shows that (x-?2) does not divide the cubic. In fact f(?2) = 4-2?2 Check for typos and try again. Once you have done the division, you will be left with a quadratic, which you can then solve in the usual way.

Science
you have a right triangle. Shouldn't be too hard to get one of the angles, eh?

Science
another right triangle.

Science
draw the parallelogram. The two vectors have magnitude 3x and 5x, so (3x)^2 + (5x)^2 - 2(3x)(5x)cos(120°) = 35 find x from that...

mathematics
impatient much?

mathematics
average speed is totaldistance/totaltime: (100+40)/(8+2) = 14 km/hr more like a bicycle, at that speed.

Math
P(9,4) = 9*8*7*6 C(9,4) = P(9,4)/4!

physics/calculus
the product rule. Both t and y are functions of t, so d/dt (bty) = b(y dt/dt + t dy/dt) = b(y + ty')

Math
5P4 = 120 3*2*5

Math
c'mon. Just substitute values for n, from 1 to 5: a1 = 3(4*1-1) = 3(4-1) = 3(3) = 9 and so on

Math
If his average so far is x, then 9x+9 = 10(x-2) x=29 9*29+9 = 270

Algebra
if the width is w, then the length is w+7, so the diagonal is w+14: w^2 + (w+7)^2 = (w+14)^2

maths
well, the angle ? between the two boats' headings (not bearings!) can be found via the law of cosines: 12^2 = 8^2+10^2 - 2*8*10 cos?

Math
how can angle BAC be measured in cm?

Math (Calc) (Differential Equation Solution)
huh? what's to start? The 1st equation is the solution to the second. All you have to do is find C such that y(x^2+y) = C goes through (0,2). 2(0+2) = C

math
well, 184/8 = 23, so ...

math
If the original price was x, then 1.4x*.95 - 1.4x*.90 = 14 x = 200 1.4*200 - 1.4*200*.8 = 224 so, the profit would be 24, or 12%.

physics
the weight of the man is unaffected by all the horizontal pushing and shoving: mg = 60kg * 9.8 m/s^2 = 588N

physics
since speed = distance/time, just plug in your numbers: ((2?*0.6)*5 m)/(2s) = 3? m/s

Math
If the westbound car has gone a distance w, then w^2 + 24^2 = (3w+4)^2

Math
(1/2)(1/4)w = 1/4 ...

Algebra 2
Let the amounts be x,y,z. Then the facts are: x+y+z = 15000 y = x+2000 .05x + .06y + .04z = 730 Now just solve for x,y,z

math

Trigonometry
no!! it is an ellipse. when t=0 you are at the right side, ready to move up and to the left: counterclockwise. http://www.wolframalpha.com/input/?i=plot+x%3D2cost%2B2,+y%3D3sint%2B3,+t%3D0+to+pi%2F2 better review how to plot points!

Trigonometry
well, x starts at a max and decreases y starts at the center point and increases. if that doesn't help, note that the ball is moving from (4,3) toward (2,6) care to try again?

Math
P(match) = 1/6 so, E = 20/6 * 5 - 20 ? -3 surprise, surprise -- the house wins. You only win 5/6 ticket per game. But it costs a whole ticket to play.

sir steve help me reiny reiny
small books! 10.98kg * 1book/54.9g = 10980/54.9 g/book = 200 g/book

maths
1 - 1/3 - (2/3)(2/3) = 2/9

Math Trigonometry
17sec^2(?)-13tan(?)sec(?)-15=0 17+17tan^2? - 13sec?tan? - 15 = 0 13 sec?tan? = 17tan^2? + 2 169 sec^2? tan^2? = 289tan^4? + 68tan^2? + 4 169tan^4? + 169tan^2? = 289tan^4? + 68tan^2? + 4 120tan^4? - 101tan^2? + 4 = 0 (24tan^2?-1)(5tan^2?-4) = 0 tan^2? = 1/24 or 4/5 ...

math
If it is now N, then in t years it will be N(1.02)^t

Math
(3/2 * 4/5)^2 = 36/25 = 1.44 so, 44% bigger

math
since AB=5, AC=12, BC=13 ABC is a right triangle. Similarly, ACD is a right triangle. So, the area should be easy to figure out, eh?

math
(a) 3 (b) 16 (c) 76

math
assuming you meant h(t) = 50+30t-5t^2 = 5(10+6t-t^2) max height is at t = -b/2a = 6/2 = 3 so, what is h(3)?

physics
pressure = force/area = N/m^2 so, plugging in your numbers, (1200*9.8)/(.06/4) = 784kPa or 115 psi If you mean each wheel is .06m^2, then divide that pressure by 4.

maths
3,4cm:17km = 1cm:5km = 1:500000

physics
r is distance (m), so assuming that x and y are also distance, a(m) = m, so a is just a constant b(s)(m) = m, so b = 1/s velocity = r' = ax' + by + bty' acceleration = r" = ax" + by' + by' + bty" = ax" + 2by' + bty" where ' ...

Math
(78/12 + 8/3) ------------------- = 55/23 (78/12 - 8/3)

geometry
try this: https://artofproblemsolving.com/wiki/index.php?title=2006_AMC_12B_Problems/Problem_23

math
(999-99)/11 = 81.81 so, there must be 81 multiples of 11 between 100 and 999 99+81*11 = 990 99+82*11 = 1001

math
http://www.wolframalpha.com/input/?i=plot+y%3Dx%2F(x%2B1)%5E2,+y%3Dx%5E5%EF%BC%8Dx

Physics
I'm having a bit of trouble with F. Force is in units of N = kg-m/s^2 Having v^2 there makes the units m^2/s^2. How do you get rid of the extra meters? Anyway, when you fix that, just remember that F = ma, so a = F/m. Just add that to the -9.8 m/s^2 of gravity, and find ...

Maths
the bug gains 1m each 2 minutes after 20*2 minutes it has climbed 20 meters During the 41st minute it climbs to 30m and is done.

maths
if there are b boys and g girls, b-1 = 2g 5(g-1) = b 5g-5 = 2g+1 3g = 6 g = 2 so, b=5 There are b+g=7 children

math
s:g = 3:2 = 9:6 g:r = 3:5 = 6:10 s:g:r = 9:6:10 9+6+10 = 25 so, we have s:g:r = 90:60:100 90+60+100 = 250

math
3b+4a+6m = 29 2b+6a+3m = 23 multiply the 2nd equation by 2, then add the two equations.

math
hits: 3*2 ? 5 7*6 ? 6 7*6 ? 4*7 2*5 = 5*2

math
3*60 = 2*90

algebra
How can 3 be a 2-digit number??? t = tens digit u = units digit so, the value of the number is 10t+u t+u = 6 10u+t = 10t+u + 36 The number is 15

algerbra
11s+4c = 93 9s+2c = 71 double the 2nd equation: 11s+4c = 93 18s+4c = 142 subtract the top from the bottom: 7s = 49 s = 7 11s+4c=93, so 77+4c = 93 4c = 16 c = 4 So, they sold 7 senior and 4 child tickets

algebra
11s+4c = 93 9s+2c = 71

Math
time = distance/speed so, figure average speed as (total distance)/(total time)

Math
correct. assuming that the ball isn't spinning in reverse, in which case it's green.

Math
not really. Aside from being incomplete, you did find that you can get 10 tickets along each side of the square. So, there are 10^2 = 100 tickets

Math
He can land anywhere he wants between A and B. If you want to find the path of least time, however, you need to minimize ?(x^2+12^2)/4 + (16-x)/8 where he lands x km from point A.

Math
why worry about the area? You are interested in the perimeter. One lap around the field covers 4*50 = 200 meters. Now, how many laps in 3000 meters?

math algebra
x+y = 400 .80x + .85y = 400-68 ...

math
why are you dividing? Does it even make sense to divide one dimension by another? The round cake has volume and area ?r^2h = ?(7/2)^2(2) = 76.97 in^3 ?r^2 + 2?rh = ?(7/2)^2 + 2?(7/2)(2) = 82.47 in^2 The rectangular cake has volume and area lwh = 6*9*2 = 108 in^3 lw + 2(lh+wh...

math
x/3 + 10 = 3x/4 4x + 120 = 9x 5x = 120 x = 24 The tank is 3/4 full, so 6 more gallons are needed.

Calculus
tossing in that extra x factor makes it beyond elementary functions, as shown here: http://www.wolframalpha.com/input/?i=%E2%88%AB(x+cos%5E2(x)sin(x))%2F(a-cos(x))+dx

Calculus
well, the first thing is to get rid of all those "nx" things. Let u = nx and we have 1/n ?(cos^2(u)sin(u))/(a-cos(u)) du now let v = a-cos(u) dv = sin(u) du cos(u) = a-v 1/n ?(a-v)^2/v dv Now it's simple.

Math
4000-460

math
the formula for y (distance) is bogus m/s^3 * t^2 = m/s the units don't work out right. It could be that you meant x = 4t + t^2 y = 2t + 2t^2 If so, then (a) set x=y and solve for t (b) set the speeds equal and solve for t

math
t:g = 13:8 g:b = 2:3 = 8:12 t:g:b = 13:8:12 ...

calculus
a good place to start is this site, with several useful examples. See what you make of it. http://tutorial.math.lamar.edu/Classes/CalcII/PowerSeries.aspx

Math
well, duh: 2222 or 4444

math
If the quantities of coins are x = \$1 y = \$2 z = \$5 then we are told x = 9z y = 8z x+2y+5z = 90 now solve for y

English
1 -- abandon, forsake

algebra
find the midpoint of the given segment: (0,-3) find the slope of the segment: -5/3 so, the slope of the bisector is 3/5 Now we have a point an a slope, so the perp. bisector is y+3 = 3/5 (x-0) or, in slope-intercept form, y = 3/5 x - 3

Math
clearly, the circle is (x+6)^2 + (y-7)^2 = r^2 So, I suspect a typo. Check your coordinates again, and recall that a circle with center at (h,k) is (x-h)^2 + (y-k)^2 = r^2 Once you fix your error, just find how far away it is from (4,-2).

Math
y+5 >= 7 subtract 5 from both sides: y >= 2 so, y could be less than 12 or greater than 12 for example, y=3 y+5 = 10 >= 7 y=20 y+5 = 25 >= 7

math
I assume you meant that each coin is 1/8 inch thick. Recall that the surface area of a cylinder is a = 2?r^2 + 2?rh = 2?r(r+h) Now just plug in your numbers.

Math
\$k = 100k cents. So, p lbs costs 100k cents. Now you can easily see what 1 lb costs, right?

Math
well, he started out with 100d cents, right?

math
you might start here. Make a flowchart that reflects the logic of the code. http://www.jiskha.com/display.cgi?id=1495379575

Math
Let's start with Physics and Chemistry. at most 30% passed physics at most 28% passed chemistry so, at most 58% passed either of the two subjects. That is, the % who failed both is at least 42% That is 100-(30+28)% Now extend that to the other subjects.

Math
x/8 + 14 = x

Math
clearly a negative answer makes no sense. How did you arrive at your result?

Math
just like the goldfish problem. What do you think?

Math
suppose you divide a pound of tea in halves. How many are there?

Math
ok. how many half-pound pkgs in a whole pound? Multiply that by 2 1/2

maths
6.25^(1/2) = 2.5 2.5^3 = 15.625 or, using fractions, 6.25 = 25/5 (25/4)^(3/2) = 125/8

Math
Surely you can see that there is something missing where you say one this of the remainder earn salaries between 15000 and 18000 how much is "one this" ?? Do you not read what you post?

Math
this is just like the goldfish problem. What do you think? Of course, it will help if you fix the missing information...

Math
1 - 1/5 - (4/5)(3/8) = 1/2

Calculus
Hmmm. The y-axis does not form part of the boundary. Each square of thickness dx has a base that is y=x^2-1 in width. So, adding up all the squares, the volume v is ?[1,2] (x^2-1)^2 dx = 38/15

Chemistry
25ml of 1.0M contains 0.025 moles of solute. So, how many grams is that for this compound?

math
xy = k now just plug in your numbers.

math
45:9000 = 1:200

math
?u is real only for positive u. So, that means ?(x+4) is real only for positive values of x+4: x+4 >= 0 x >= -4

Calculus
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