Monday
September 15, 2014

Posts by steve


Total # Posts: 24,948

Math
just subtract his initial loss from the subsequent profit: 1580-415 = ?
August 20, 2014

Algebra
sounds good. You might also note that for an exponential function y = f(x), log(y) is linear.
August 20, 2014

Geometry - eh?
Hard to say. Just noting the degrees separating the hands tells nothing about the actual time. And, since you don't specify which hand is at 70 degrees, that's no help either. Want to rethink the question?
August 20, 2014

Math
If you mean (225-256)^2 that's just (-31)^2 = 961 If you mean 225-256^2 that's -65311
August 20, 2014

Algebra
easy. Note that y^3 / y^10 = y^3 / y^3*y^7 The y^3 factors cancel, and you are left with 1/y^7 Or, use the rule that in division, you subtract exponents, so y^3/y^10 = y^(3-10) = y^-7 = 1/y^7
August 20, 2014

college algebra
It's already factored! Want to rephrase the question?
August 20, 2014

maths
what do meters have to do with anything? If the equation is 3 cos x = 25x, that's one thing. If not, fix the equation, but leave the m^2 out of it.
August 20, 2014

MATHH
The slope of the line joining those two points is (4+7)/(3-2) = 11 But, you are supposed to find the slope of any perpendicular line. That is -1/11.
August 20, 2014

math
1. reflect through the x-axis 2. reflect through (0,0) 3. a translation, but you are missing a sign.
August 20, 2014

math
You have a/b = 4/5 a/c = 6/11 You want b/c = (b/a)/(c/a) = b/a * a/c = 5/4 * 6/11 = 30/44 = 15/22
August 20, 2014

math
B gains 100 yards every minute. So, after 10 minutes, B has lapped A once. C gains 100 yards on B every minute, so after 10 minutes C has lapped B. Thus, after 10 minutes, A has gone 7 laps, B has gone 8 laps, C has gone 9 laps, and all are even again.
August 20, 2014

Math
-8 is less than any of them. All the negatives come first. The || values are all positive. So, (C) is correct
August 20, 2014

Geometry
In an equilateral triangle, the median is the same as the altitude. If the side is s, the median is √3/2 s. Each median extends from a vertex to the midpoint of the opposite side.
August 20, 2014

algebra
I get this far √a-√b = √18-√6 and have trouble figuring out what "nd multiply root5" means. How about filling in the rest using math symbols?
August 20, 2014

math
None are. They are, however, supplementary.
August 20, 2014

Maths
that would be 645.7/8 Drag out your calculator of choice to evaluate that quotient.
August 20, 2014

Algebra
D = 1.2√H Now just plug in H=12000
August 20, 2014

Trigonometry
Looks like time to review the basic trig functions. It always helps to draw a diagram. (1) 12.75/x = sin 48° (2) sin x = 3.1/9.4 (3) 16/x = tan 9°
August 20, 2014

Math
mi/hr * 1hr/60min * 1min/60sec * 5280ft/mi Note that the units all cancel out, leaving ft/sec Actually all of the factors will work, if you divide by 1mi/5280ft. However, since one usually wants to multiply, I'd say (d) would not be used.
August 19, 2014

math
y = x^3 All of the odd powers look basically the same as x^3. Play around at wolframalpha.com to see.
August 19, 2014

math
hmmm. Is it 4? Is 4^2 = 36? Does 4 have 3 as a factor? Better read what I wrote, and this time pay attention.
August 19, 2014

math
I'd make that 6, since 81 = 3^4. p^2 must have some powers of 3 in it, else GCF(p^2,81) = 1. GCF(36,81) = 9 9 would be better, but we needed an even integer.
August 19, 2014

English
none that I know of, but there are plenty which will correct your spelling of "grammar."
August 19, 2014

Physical Science
The airspeed is the speed relative to still air. In the absence of other factors, the airspeed is the same as the ground speed. If the wind is blowing, the wind velocity must be added to the bird's velocity in still air (airspeed), to get the velocity relative to the ...
August 19, 2014

physics
total distance: 108+42 = 150km total time: 6hr avg speed: 150km/6hr = 25 km/hr
August 19, 2014

math STEVE
you could have appended the correction to the original post. Anyway, 783-500 = 283 Apparently he makes no commission on the first $100. Assuming that, he makes 0% on 100 = 0.00 5% on 400 = 20.00 10% on 283 = 28.30 Total = 48.30 If I made a mistake on the first $100, make the ...
August 19, 2014

math
read it. The last sentence makes no sense.
August 19, 2014

math
#2. Assuming all the rest tried out for pitcher, then we have 1/8 + 1/3 + 1/4 = 17/24 So, the remaining 7/24 must have tried out for pitcher. #1 is garbled.
August 19, 2014

math
I did it this way 20*34 = 680 (total of all 20 numbers) 4*45 = 180 (total of the 4 numbers with mean 45) 680-180 = 500 (missing total, due to the other 16 numbers) 500/16 = 31.25 Your final answer is so huge it should have been a tipoff. The mean of the other 16 should have ...
August 19, 2014

math
6(y-7)-6 = 6y-48
August 19, 2014

math
no. my typo of 41 is a boo-boo, but your answer is correct. You correctly answered the question that was asked.
August 19, 2014

math
looks good. Does it work? Jack is 45 5 years ago, he was 41 40 = 46-6 OK
August 19, 2014

Science - go with DrBob
Dang. I forgot about the molecules, not atoms.
August 19, 2014

Science
you know Avogadro's Number, AN=6.023*10^23 Also, 1 mole occupies 22.4L (22400 cm^3) at STP. (a) (50dm^3)/(22400cm^3) * AN = ? (b) (10cm^3)/(22400cm^3) * AN * 19 = ? (because F has 19 nucleons/atom)
August 19, 2014

Math
(a) note that as x increases by 4, y increases by 2. Then, as x increases by 2, y increases by 1. (b) and (c) work the same way. Starting at the first point, note that the changes in y and x have the same ratio. That is, the slope remains constant, and since the middle point ...
August 19, 2014

Science
well, they would be nice to know, but the crew of the carrier would presumably include a doctor and weather guy. I'd pick D over A. Modern ships have lots of computers on board, and a knowledge of physics would come in handy in handling the ship.
August 19, 2014

math
using substitution, 7/y = 31-5/x so y = 7/(31-5/x) = 7x/(31x-5) 7x+5y=29xy y = -7x/(5-29x) 7x + 35x/(31x-5) = 29x * 7x/(31x-5) 7x(31x-5) + 35x = 203x^2 14x^2 = 0 As Damon noted, x=0 is not allowed, so there are no solutions. If you plot the difference between the two functions...
August 19, 2014

math
looks like (b) to me (a) is distributive
August 19, 2014

math
assuming both values are -1, even powers of -1 are +1 odd powers are -1 so we have -1 - +1 = -2 Or, you could factor out (-1)^1988 and have (-1)^1988(-1 - 1) = (+1)(-2) = -2
August 19, 2014

quadratic function
let x be the time since midnight, and y be the water level. We have y(11.75) = 0.46 y(23.50) = 0.46 the vertex is thus (17.625,2.16) Now you have three points, so you can determine the parabola, and you want x where y=1.
August 19, 2014

math
If the length is x, the width is x-.5 so x(x-0.5)=3 Now just solve for x
August 19, 2014

math
Hmmm. If you had said three more than twice its width, I'd have immediately said the room was 5x13. But, now we have to use some algebra. w(3w+3) = 65 w = 4.1815 for the perimeter, we want 2(w+3w+3)=39.452
August 19, 2014

algebra
I'll take a stab at it. As written, it appears to be (-1^2+11^2)(11^2- -7^2) (-1+121)(121- -49) (120)(170) 20400 If we assume the usual carelessness with parentheses, per Damon, then we have ((-1)^2+11^2)(11^2- (-7)^2) (1+121)(121-49) (122)(72) 8784 I can't believe you...
August 19, 2014

statistics
better check your dairy almanac for stuff like this.
August 19, 2014

Math
why is google like a search engine?
August 19, 2014

Math
depends on whom you ask Most say 5 rounds up Some say 5 rounds to the next even digit, so 35 rounds to 40 45 rounds to 40 Better check with your instructor or text to see which answer will get you marked correct.
August 19, 2014

Science
weight(N) = mass(kg) * 9.81 m/s^2
August 18, 2014

Advanced algebra
looks discrete to me
August 18, 2014

math
15*5+2 = 77 15*6+2 = 92 So, only two of them
August 18, 2014

Algebra 2
midway between the two extremes is (32.85+31.15)/2 = 32.00 So, |x-32.00| <= 0.85
August 18, 2014

Programming
read amount, months; show_deposit(amount,months); function show_deposit(amount,months) { deposit = amount/months; print deposit; }
August 18, 2014

maths
Hmmm. you are mixing up price per kg and per cob, with no indication of how many cobs per kg.
August 18, 2014

Maths
50-y You can easily do stuff like this if you use an actual number, and then study how you solved it. Suppose you had R50 and spent R10. What is the change?
August 18, 2014

Please Help ! Analytic Geometry
try this solution: http://www.jiskha.com/display.cgi?id=1408162681
August 18, 2014

Algebra
Not bad, except that 6.5-4 ≠ 1.5
August 18, 2014

Math
assuming the 2300 included the 15% profit, the value was 2300(0.85) Now divide that by 100 to get the per-share price.
August 17, 2014

Alegbra
you are correct. To see its graph, type that in at wolframalpha.com
August 17, 2014

math
assuming the smaller rectangle is enclosed by the larger, we have small rectangle: w(2w-1) large rectangle: (w+2)(2w-1+2) Assuming the shaded region is the difference between the two rectangles, we have (w+2)(2w+1)-w(2w-1) = 86 w = 14 So, the smaller is 14x27, with area=378
August 17, 2014

trig
since the spring starts at (0,-17), we know that D(t) = -17 e^-at cos(kt) since the period is 1/13, k = 26π and we have D(t) = -17 e^-at cos(26πt) Now, we know that the amplitude has decreased to (16/17)^(t/3) That means that a = -1/3 ln(16/17) = .02, and D(t) = -17 ...
August 17, 2014

geometry
Of course the 3rd side can be 5 or 9. That just makes an isosceles triangle. So, you want all the numbers n such that 4 < n < 14: 5+6+7+8+9+10+11+12+13 = 81
August 17, 2014

geometry
as a hint, suppose you joined the two sticks at the end. Now consider rotating the smaller one, from being end-to-end with the larger one, to overlapping it. What's the max and min possible length for the third side? Now list all the integers in that range and add 'em up.
August 17, 2014

geometry - again?
another of these triangle problems? Have any ideas of your own on this one?
August 17, 2014

physics - Go with Damon
As usual, go with Damon. He tends to think things through more carefully.
August 17, 2014

physics
as usual, s = 1/2 at^2 Since g is acting downward, the net acceleration is 32-9.8 = 22.2 m/s^2 upward s = 1/2 * 22.2 * 4.1^2 = 186.6m Actually, the question is poorly worded, since it implies that the net acceleration is 32 m/s^2, even after including the effects of gravity. ...
August 17, 2014

math
more formally, for the purposes of homework, just use the comparison test |cos(1/x)| <= 1, so x cos(1/x) < x which -> 0
August 17, 2014

programming
in unix, there is usually a file named /usr /dict /words It may be named somewhat differently, or be located somewhere nearby, but you can probably find it. If not on unix, look for some such file name. As for rhyming, good luck. That is where the art of programming comes in. ...
August 17, 2014

maths
p'(x) = 4x^3 + 3ax^2 + 2bx + c since p'(0) = 0, c=0 and p'(x) = x(4x^2+3ax+2b) Since p' has no other roots, 9a^2-32b < 0 a^2 < 32b/9 p(-1) = -4+3a-2b+c p(1) = 4+3a+2b+c It appears that the answer is (c) Consider x^4+x^3+x^2 min is at (0,0) max at (1,3) ...
August 17, 2014

Math
(22-2w)(26-2w) = 396 w = 2 24*26-396 = 228 No, not enough brick 22*26 - (22-2w)(26-2w) = 160 w = 1.8 Not sure how #3 relates to #1 as with all such problems, divide the fencing evenly between the lengths and the widths. That means that a square 50/4 feet on a side will provide...
August 17, 2014

science cbse school
clearly the masses total 5+2.5 = 7.5 kg So, what's 10/7.5?
August 17, 2014

Algebra
It appears that the 0 was a typo for ), making the problem 5(14-2)^2/2 = 5*12^2/2 = 5*144/2 = 360
August 16, 2014

Geometry
The three lines intersect to form a triangle. Naturally, there is one circle inside the triangle, and three circles outside the triangle, all of which touch the three lines. The three lines intersect at (2,5),(5,-1),(-3,-5). If we call those vertices A,B,C, then the opposite ...
August 16, 2014

Could you please check my answers.
1) - 1.8 - 3.9 a- -2.1 b- 5.7 c- 2.1 d- -5.7* 2) -7 = 5 a- -2* b)12 c) -12 d) 2 3) -6.1 + 1.7 a-7.8* b- -4.4 c- -7.8 d- 4.4 4) A mountain climber ascends a mountain to it peak. The peak is 12,740 ft above sea level. The climber then descends 200 ft. to meet a fellow climber. ...
August 15, 2014

Geometry
for sides a<b<c c-b < a < c+b So, if 3L is the longest side 15-L < 3L < L+15 15 < 4L < 2L+15 L > 3.75 L < 7.5 So, the extreme is 7,15,21 for a perimeter of 43
August 15, 2014

Trigonometry
3 rides = 3 * 12.4 = 37.2 revolutions So, the angle moved is 2pi * 37.2 = ? radians The distance traveled is 2pi * 37.2 * 18.3 = ? meters
August 15, 2014

Precalculus/Trig
(cos+1)/sin^3 = csc/(1-cos) multiply by (1-cos) (1+cos)(1-cos)/sin^3 = csc = 1/sin (1-cos^2)/sin^2 = 1 sin^2/sin^2 = 1 1 = 1 (sin+cos)(tan+cot) = sec+csc sin*tan + cos*tan + sin*cot + cos*cot = sec+csc sin^2/cos + sin + cos + cos^2/sin = sec+csc (sin^2+cos)/cos + (sin^2+cos^2...
August 15, 2014

math i need help 3 questions
I'll do #1. How about you show some effort on the others? Just write the words in symbols. If the fraction is n/d, then we are told n/d = 3/4 (n+4)/(d-4) = 4/3 Work through all that, and you have n=12,d=16 check: 12+4 / 16-4 = 16/12 = 4/3 OK
August 15, 2014

math
set it up as a units conversion problem. b books = d dollars, so b bk/d dol = 1 d dol/b bk = 1 That is, books go at the rate of b/d books/dollar, or d/b $/bk Now, you want to convert d books to dollars. You can always multiply by 1, so do it to cancel the units you don't ...
August 15, 2014

math
Nope. (D) Did you draw a diagram? Do so, and label the points. You will have 3 equal sections: AB,BC,CD. AC is twice as long as CD.
August 15, 2014

math
If b lies on ac, then ab+bc = ac x+3 + 2x = 4x-5 x = 8
August 15, 2014

compose
I'm sure that there are those who would consider any of the choices to be the best. It's a purely subject opinion, based on one's own criteria. And what does that (or either of you other posts) have to do with homework?
August 15, 2014

math
nothing to solve. However, if you meant x^2-3x+4 = 0, the two complex values of x that make it true are 3/2 ± √7/2 i If you meant to type x^2-3x-4 = 0, then that factors to (x-4)(x+1) = 0 and it should be clear which values of x are solutions there.
August 15, 2014

trigonometry
If you mean 37°49', then clearly sin 37°49' = 1.5/x now just solve for x, the length of the plank. Oh, and review your basic trig functions.
August 14, 2014

EEeeeeewwww
eeewwww. You've ruined unicorns for me forever!
August 14, 2014

Math - eh?
no idea what all the carets represent.
August 14, 2014

help me
how about you list the six steps. Then apply each step. We'll be happy to check your solution. Wouldn't hurt to bone up on your English, as well...
August 14, 2014

Programming
Try something like this: main() { int x[1000],y[1000],i; for (i=0;i<1000;i++) {read x[i]} y = rev(x,1000); for (i=0;i<1000;i++) {printf("%d ",x[i]} } int *rev(*int,n) { int y[1000],i; for (i=0,n--;i<1000;i++,n--) {y[i] = x[n-i]; return y; }
August 14, 2014

math corrections
Since no coin duplicates the amounts of combining other coins, the number of items could be as many as 4C1 + 4C2 + 4C3 + 4C4 = 15 Note that the sum of the nth row of Pascal's triangle is 2^n, but we are missing 4C0=1, leaving only 15 combinations. This is also the number ...
August 14, 2014

Algebra
from eq #1, 6x = 5y-1 sub that into #2, and you get 5y-1 + 4y = 10 9y = 11 y = 11/9 Now you can get x
August 14, 2014

Algebra
12x+18y+8 <= 80 x+y <= 7 x > 0 y > 0
August 14, 2014

maths
the "rays" instead of "raised" doesn't help any. I read it as ((36/25)^(3/2)) ^ (5/3) due to the sly "whole" meaning "all that has come before". Now, since 36 = 6^2, 36^(3/2) = 6^3 25 = 5^2, 25^(3/2) = 5^3 Now, raise those to the 5/3...
August 14, 2014

math
rectangle: 2(x+2x) = 24 3x = 12 x = 4 So, the rectangle has area 2*4*8 = 64 Now, the square has side 8, so its perimeter is 32.
August 14, 2014

math
the other side, x, satisfies 4.2^2 + x^2 = (x+14)^2 Hmmm. You sure there's no typo?
August 14, 2014

math
a convex polygon with five equal sides. if you google that, you will see many images and descriptions.
August 14, 2014

math
since p = 2(x+y) = 8y, x+y = 4x x = 3y y:x = 1:3
August 14, 2014

Math
see the many related questions below
August 14, 2014

Math
OK. First, it's lookout, not lockout. The man is 25-1.7 = 23.3m up. If the building is at distance x from the tower, and has height h, we have 23.3/x = tan 70°20' (h-23.3)/x = tan 12°40' Now, you can eliminate x, and then solve for h: 23.3/tan70°20'...
August 14, 2014

trigo
As I interpret the data, it appears that the law of cosines will provide our answer. We want the supplement to θ, where 15^2 = 6^2+9^2 - 2(6)(9)cosθ cosθ = -1 Nope, that doesn't work. Maybe you can just describe the figure, giving labels to the points of ...
August 14, 2014

math
If x at 9%, .09x + .10(26000+3x) = 27650 x = 64231
August 14, 2014

Trigonometry
consider the pentagon as 5 isosceles triangles, each with vertex angle of 72°, and sides of 1.5 (the radius). Now you can easily calculate the base of each triangle. The perimeter is 5 times that.
August 13, 2014

Algebra 2
(x-3) / 2x * 6x^2 / 5 (x-3)(6x^2) / (2x)(5) (x-3)(3x)/5 and you can massage that as you will
August 13, 2014

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