Saturday

October 25, 2014

October 25, 2014

Total # Posts: 26,101

**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*

**Complex Numbers**

if z = x+yi, you have two equations: (x-2)^2 + (y-2)^2 = 23 (x-8)^2 + (y-5)^2 = 38 They intersect at (1/5(20±3√10), 3/5(5∓2√10)) check: (1/5(20+3√10)-2)^2 + (3/5(5-2√10)-2)^2 = 23 You can verify the other.
*August 13, 2014*

**Precalculus**

If z = a+bi, we have (1+i)(a+bi) - 2(a-bi) = -11+25i Expand all that out and you get (-a-b)+(a+3b)i = -11+25i So, that means that -a-b = -11 a+3b = 25 a=4 b=7 So, z = 4+7i
*August 13, 2014*

**Precalculus**

I'd just multiply: (4-5i)^2 + (a+8i)(4-5i) + (-39+bi) = 0+0i Expand all that out and you have two equations in a and b. I get a = 2 b = 18 So, that leaves us with z^2 + (2 + 8i) z + (-39 + 18i) = 0 and the other root is thus -6 -3i
*August 13, 2014*

**math test review**

You know that 5^2 = 25 6^2 = 36 34 is less than 36. Now what do you think?
*August 13, 2014*

**Math**

no such number exists. Such terminology is bogus. If you mean 41 ten-thousandths, that would be 0.0041 You can have 41 thousand, but not 41 ten thousand.
*August 13, 2014*

**Math**

150% none (should be 70%) recall that 1.0 = 100%
*August 13, 2014*

**Calculus (need help with only d and e)**

The 2nd pill is shifted by 60 minutes. So, if the 1st pill is modeled by f(x), the 2nd pill will be modeled by f(x-t). Now just work with the new f(x).
*August 13, 2014*

**maths**

If you mean 9^(2x+1) = 81^x / 3^x expressing all as powers of 3, we have 3^(4x+2) = 3^3x so, 4x+2 = 3x x = -2 check: 9^-3 = 81^-2 / 3^-2 = 9^-4/9^-1 = 9^-3
*August 13, 2014*

**algebra**

your writing is so full of typos it's incomprehensible. When you get an answer, test it to see whether it works in the original equation.
*August 13, 2014*

**Algebra**

you could easily have verified it on your handy dandy calculator. Can't believe you went to the trouble of posting such an easy thing to check.
*August 13, 2014*

**math**

(25+12*15)*.12
*August 13, 2014*

**Algebra**

Your work so far is correct.
*August 13, 2014*

**statistic**

.20 * .30
*August 13, 2014*

**statistics**

Oops. I misread (b). My answer is ~rain & windy
*August 13, 2014*

**statistics**

(a) .20 * .30 = .06 (b) (1-.20) * .30 = .24 (c) .20 + .30 - .20*.30 = .44 (d) (1-.20) + (1-.30) - (1-.20)(1-.30) = .94 Note that (d) = 1-(a)
*August 13, 2014*

**math**

2pi = 6.28 so, you have 2pi r = C 6.28r = 27 now just divide by the 6.28 as usual to get r.
*August 13, 2014*

**Math**

You know that for the parabola y^2 = 4px It opens to the right The LR is 4p (So, if the shifted parabola is (y-k)^2 = 4p(x-h), our points and LR say (1-k)^2 = (3-h) (5-k)^2 = (-5-h) so, the parabola is (y-4)^2 = (x+6) So, now you have a 3rd point: the vertex at (-6,4) Now it&#...
*August 13, 2014*

**Algebra**

#1. x(2400-2x) #2. x(1800-6x)/2 Both of these are just parabolas, where the maximum area occurs at the vertex of the parabola. Recall that for y = ax^2+bx+c, the vertex is at x = -b/2a
*August 13, 2014*

**maths**

clearly, d = 3/2. So, if the first term is a, a(a+3d) = 34 a(a+9/2) = 34 . . .
*August 13, 2014*

**math**

Surely your text has sections on these topics. I expect that the accompanying graphs and sample problems there will be at least as good as any impromptu explanations here. Do a google on any of the above topics for many discussions. After that, if there's some kind of ...
*August 13, 2014*

**math**

http://www.wolframalpha.com/input/?i=x%2B2y-z%3D6
*August 13, 2014*

**maths**

total distance: 240 miles total time: 120/60 + 120/40 = 2+3 = 5 hours avg speed: 240/5 = 48 mph
*August 13, 2014*

**geometry**

why bother with a? Just prove x=7. 3(2x+4)+18 = 72 6x+12+18 = 72 6x = 42 x = 7
*August 13, 2014*

**maths**

3@5 = 3(5-3) = 6, so 4@(3@5) = 4@6 = 4(6-4) = 8
*August 13, 2014*

**algebra**

almost. If 2n=78, n=29 If 1/2 n = 78, n = 156 We customarily use a caret, as in 3^4, to indicate powers.
*August 13, 2014*

**math - typo**

10% of 4 is 0.4 None of the choices works. I suspect a typo in your presentation.
*August 13, 2014*

**Math**

If there were x 2-pointers and y free throws, then we know x+y = 18 (add the shots) 2x+y = 35 (add the points) Now just solve for x and y.
*August 12, 2014*

**math**

just as 5-3 = 2, 5/6 - 3/6 = 2/6 However, the instructions say to write the simplest form, so 1/3 would be my choice.
*August 12, 2014*

**Math**

Does 7 divide 3? Nope, so that cannot be a factor of 3u^3... List all the factors of each term: 3 u^3 x^5 y^8 3 7 u^6 x^5 Now pick the highest power of each prime or variable that appears in both terms: 3 u^3 x^5 That is the GCF.
*August 12, 2014*

**math**

you already have one pair: (1,1.50) Now just pick any positive integer, and multiply it by 1.50. That will give you other pairs: (2,3.00) (102,153.00) (9231,13846.50) For convenience of graphing, I'd stick with small numbers, though! :-)
*August 12, 2014*

**math trigonometry**

Draw a diagram, as usual. If the post is x meters from the house, which has height h, h/x = tan 45° = 1 So, h = x (h-20)/x = tan 30° = 1/√3 But, h=x, so (h-20)/h = 1/√3 h-20 = h/√3 (1-1/√3)h = 20 h = 20/(1-1/√3) = 47.32 m
*August 12, 2014*

**Math**

Oops. g◦f and f◦g are not onto, since (g◦f)(0) = 0 (g◦f)(1) = 2 And there is no x such that (g◦f)(x) = 1 (f◦g)(0) = 1 (f◦g)(1) = 1 (f◦g)(2) = 4 and there is no (f◦g)(x) = 2
*August 12, 2014*

**Math**

clearly g is not 1-1. For example, g(3) = g(2) Also, it is clear that both f and g are onto. Some good discussion can be found here: http://www.csee.umbc.edu/~stephens/203/PDF/7-3.pdf f◦g = 3g+1 = 3⌊x/2⌋+1 g◦f = ⌊f/2⌋ = ⌊(3x+1)/2⌋...
*August 12, 2014*

**arithematic**

the middle value is (51+64)/2 = 57.5 That is 6.5 away from each end, so |x-57.5| <= 6.5 See the graph at http://www.wolframalpha.com/input/?i=|x-57.5|+%3C%3D+6.5
*August 12, 2014*

**arithematic**

If the dimensions of the garden are x and y, with the building along side x, then x+2y = 81 So, the area (xy) is (81-2y)y = 81y - 2y^2 This is a parabola, with vertex at y=20.25 Now you can figure the other dimension. I suspect you meant to say 80 ft of fencing, but only you ...
*August 12, 2014*

**Math**

If the strip has width w, the pool is 60-2w by 80-2w So, (60-2w)(80-2w) = 1/6 (60)(80) Now just solve for w.
*August 12, 2014*

**Math**

If the dimensions of the whole garden are x and 2y (because there are two adjacent gardens, each x by y), 2x+4y = 100 2xy = 400 or, x+2y = 50 xy = 200 since x = 50-2y, (50-2y)y = 200 50y - 2y^2 = 200 y^2-25y+100 = 0 y = 5 or 20 So, x = 40 or 10 The garden is 10 by 40.
*August 12, 2014*

**6th grade math**

count the coins: n = d+13 count the value: 5n+10d = 440 5(d+13)+10d = 440 5d+65+10d = 440 15d = 375 d = 25 So, there are 25 dimes and 38 nickels
*August 12, 2014*

**Analytic Geometry**

(a) x^2+y^2 = 4 (b) surely you know how to figure the area and circumference of a circle of radius 2. (c) subtract that area from the area of the triangle. This is because the entire circle is within the triangle.
*August 11, 2014*

**Analytic Geometry**

Solving the equations in pairs, you find the vertices to be (2,5),(5,-1),(-3,-5) Now you can figure the incenter and inradius of the triangle. The equation of the circle is then easy.
*August 11, 2014*

**Algebra - eh?**

It appears you have something to do with the Pythagorean Theorem, but it's not immediately clear just what.
*August 11, 2014*

**coor. algebra**

work with units, just as with numbers. When doing conversions, just recall that you can always multiply by 1 and nothing is changed. You want to convert meters into miles, and seconds into hours. 3600 seconds = 1 hour So, 3600sec/hr = 1 Similarly, 1km = 1000m = 0.62 miles, so...
*August 11, 2014*

**Analytic Geometry**

Or, you can take the slopes of the sides. AB has slope 1/3 AC has slope 3/2 So, measuring as usual, angle A is arctan(3/2)-arctan(1/3) = 236.31°-198.43° = 37.88°
*August 11, 2014*

**Algebra**

all correct. Though I'd have written #2 as (9+5z)(9-5z) to associate it more readily with the difference of two squares.
*August 11, 2014*

**math**

.19a + .22b = 36.12 175a + 80b = 30080 a = 160 b = 26
*August 11, 2014*

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