April 18, 2014

Posts by Steve

Total # Posts: 21,749


not only is the premise not necessarily true, but you need to be a lot more particular about which society you're describing.

35+.18x = 71

since sin>0 and cos<0, we are in QII. So, y=1,r=4,x=-√15 sin = y/r = 1/4 cos = x/r = -√15/4 tan = y/x = -1/√15 ...

good graphing help at

math 209
only true if x=0 or x=1

40 in wheel has circumference 40pi inches 50 mi/hr = 52800 in/min so, that's 52800/40pi rev/min or, 52800/40pi * 2pi = 52800/20 = 2640 rad/min

algebra & trigonometry
w(3w+8) = 28 3w^2+8w-28 = 0 (3w+14)(w-2) = 0 w = 2

algebra & trigonometry
x^2+x-210=0 (x-14)(x+15) = 0

10cm + 286(30m+10cm)

If the tree is of height h and at distance d, then (150-h)/d = tan 50° h/d = tan 22° Now you have two equations in two unknowns, so just solve them.

(a) each number is -2 times the previous (b) I suspect a typo, since the signs do not alternate. However, a rule which works is that the nth term is n times the previous term, with sign changing when (n-1) is a multiple of 3.

More Algebra - Dividing Radicals!
2πr = 2π(5/(√2-1) = 2π(5/(√2-1)*(√2+1)/(√2+1) = 2π(5/(√2+1))/(2-1) = 10π(√2+1) (C) is correct

-3*7 = -21 -3*8 = -24 -2*11 = -22 and so on you can also use -7*3 = -21 and so on -1*23 and 1 * -23 There are oodles of possibilities

the original area is 12*14 = 168 the square piece is 6x6, with area 36 I assume you can now solve the problem.

Could you find the circumference of a circle using the exact value of pi? Why or why not?


Given: f(x) = X^2-x evaluate: f(sqrt2 + 3) I have worked out this and am stuck: (sqrt2+3)^2 - (sqrt2+3) (sqrt2+3)*(sqrt2+3)- (sqrt2 +3) (sqrt2)^2+ 3sqrt2 +3sqrt2+ 9- (sqrt2+3) 2+6sqrt2 +9-sqrt2-3 and am stuck or wrong here. Ans= SQRT2+6sqrt2 all under radical

of course. A circle of radius 12 as circumference exactly 24π Of course, if you want an exact numeric answer, that's not possible, since the value of π is an unending decimal fraction.

A seagull flies at a velocity of 10.00 m/s straight into the wind. (a) If it takes the bird 18.0 min to travel 6.00 km relative to the earth, what is the velocity of the wind?

solve how? There is no single pair of numbers for (x,y) which will work. They are the equations of lines. Any point on the line will satisfy the equation. Now, if you want to solve each for y as a function of x, then just rearrange things until y is all alone on one side. #7: ...

half-period is 6 hours, so a full period is 12 hours. So, if 2pi/k = 12, k = pi/6. The max-min=1.9-1.1 = 0.8, so the amplitude is 0.4 So, the choice is C or D. The midpoint is (1.9+1.1)/2 = 1.5, so we're still looking at C or D. Since we apparently want a cosine function, ...

Calculus I
ah, a nice related-rates problem. a = pi r^2 da/dt = 2pi r dr/dt when r=3, 8 = 2pi(3)(dr/dt) dr/dt = 4/(3pi) cm/s By the way, da/dt is 8 cm^2/s. That makes the units come out right. cm^2/s = 2pi(cm)(cm/s)

algebra and trigonometry
If the quantity of tickets is x,y,x for t5,10,15 dollar tickets, respectively, then we have x+y+z = 180 5x+10y+15z = 1900 x+z = 2y (x,y,z) = (50,60,70)


math 3
a pint's a pound, the world around so, since 16 fl oz is one pint, it should be clear. Extra credit: what's the difference between an ounce and a fluid ounce?

1/5 = 2/10

n/(n+6) = 3/4 n=18 3/4 = 18/24

Calculus (Math)
ah! good one! Looks easy, but there's some algebra and trig identities involved. Rather than slog through it here, I refer you to^5+%28csc4x%29^7 and hit the "step by step solution" button.

well, if a pie is divided into 10 pieces, are they larger or smaller than when it's cut into 5 pieces? Smaller denominator means fewer pieces, so each is larger.

1.2 * (32/10)

2(w + 4w+1) = 292

The equivalent resistance from R2 and R3 is 1/R = 1/38 + 1/18 R = 12.214 So, we now have a total R of 16+12.214 = 28.214 ohms That means our current through R1 and the R2R3 network is 6/28.214 = .212 amps Now, divide that current between R2 and R3 and Ix = .212(38/56) = .144 o...

math algebra
well, since the slope-intercept is y = mx+b I wonder where lies the difficulty???


writing and linear equations
if the angle is x, its supplement is 180-x, so just solve 180-x = 2x x=60 What's all this nonsense about x=4n+12? If you need to find "the number" then just solve that for n, given that x=60.

it is rational because it is the ratio of two integers

Look at the prime factorization of 1-10. The LCM will be the product of the highest powers of That would be 2^3*3^2*5*7 = 2520

algebra 2
y = a sin(bx+c) + d

since the coefficient of x^2 is positive, we know the parabola opens upward, so it minimum. The vertex of the parabola is at x = -1, so plug that in to get y. Or, complete the square: y = x^2+2x+1 - 8 y = (x+1)^2 - 8 y+8 = (x+1)^2 Now you can just read off the coordinates.

since the sides are all equal, s^2 = s^2+s^2 - 2s^2 cosθ cosθ = 1/2 since you can pick any side, the value for θ is good for all three angles.

math - trig
sin(x) and sin(180-x) have the same value. gotta use the law of cosines, which takes into account the change of sign for obtuse angles.

since the chord forms the base of an isosceles triangle, the other angles are 45° and 90°. The radii form the 90° angle, so 2r^2 = 4^2, and r=2√2.

No, I meant sum and difference. I started out trying the half-angle for tangent, but got bogged down. Then I saw the sums on the right and went the easy way.

using the half-angle formulas, sin(x)-sin(y) = 2 cos((x+y)/2)sin((x-y)/2) cos(x)-cos(y) = -2sin((x+y)/2)sin((x-y)/2) ta-da!

1000(1.03)(1.02) = 1050.60

well, since BCD is half of the parallelogram, I'd say that ABCD = 30 km^2

3/2 - 6/5 = 15/10 - 12/10 = 2/10 = 1/5 5 8/9 - 1 = 4 8/9 no need to worry about the fraction, since the 1 is just subtracted from the 5.

the ratio of shadow length to height is the same for pole and man, so x/6 = 20/25 now just solve for x Or, you could just say that the heights and shadows have the same ratio, so x/20 = 6/25

well, what is it for one year? Double that for two years.

To answer your question, it's an equation. Now, to solve the equation, just write it down and go through the steps to get r by itself. 3/7 r = 3/5 multiply both sides by 7/3 to get (3/7)(7/3)r = (3/7)(3/5) r = 9/35

Note that each term is 1/4 the previous one. Tn = (1/4)^n or 1/4^n On the next, it's the same ratio, but T1 = 5/16 Tn = (5/4)*1/4^n

1/2 kg * 10sweets/50g * 1000g/1kg = 100 sweets Or, you could just say that since 1/2 kg = 500g, that's 10 times 50g, so you get 10 times the sweets, or 10*10=100

You say nothing about how you know that Q is "just above" L, or what that means. I'd say (c) is the choice. You draw arcs centered at P and T, such that they intersect above and below L. Note that the arcs must have radius greater than LT=LP. I get the feeling th...

Note that angle ABC = 33 degrees. So, using the law of cosines, your distance d is given by d^2 = 300^2 + 200^2 - 2(300)(200) cos33 plug and chug

Math, science, trinogonomentry
How about you give us some angles that make sense in a triangle. The angles need to sum to 180. I realize that C is unknown, but geez, guy. What system are you using? Anyway, assuming you can actually devise some reasonable values, just use the law of sines: a/sinA = c/sinC c ...

programming concepts
here's a little perl program which should do the job. You can probably adapt it to the language of your choice. my @rates = [ {amount=>150,us=>0,canada=>0}, {amount=>100,us=>12,canada=>15}, {amount=>50,us=>9,canada=>12}, {amount=>0,us=>6,ca...

area: 3.14*23^2 circ: 2*3.14*23

Excellent Z-table site:

Division Properties of Exponents~Algebra
Unless there are some typos, all of your answers appear to be correct. Just a note: Since you correctly used the caret (^) to indicate powers in #4, I'm surprised that you didn't do it in 1-3. x2y3 is sort of easy to figure out, but in #3 it's not immediately evide...

Look up 0.7500 in your Z table. That is -.674 std from the mean. Now scale and shift it for your problem: 5 - .675(2) = 3.65 A handy place to play around with this stuff is

If you plot the points, you will see they form a right angle, with lengths 5 and 7. So, the area is 5*7/2 = 17.5

Math easy please help
Assuming you have by now figured it out, just make sure that you specify the needed accuracy. The answer is 1.30, not 1.3 Even though they are the same value, the 1.30 means that you have explicitly calculated that there are zero hundredths.

Math Urgent help please
As always, draw a diagram. Now, recalling your trig functions, it is easy to see that h/(15+5) = tan 50° now, just solve for h

that would be 30(5/2) = 75

the height of the person

same as 960/20

algebra 1 help please ASAP
mosey on over to and click on the "long division" link. It will let you divide polynomials and shows all the details.

Social Studies

Social Studies

math - typo?
6/24 is 25%, not 6/26 we need (4+x)/(24+x) = 1/4 16+4x = 24+x 3x=8 eh? we need an integer solution. I suspect a typo.

math - hmmm
revenue is demand*price r(x) = (450-7x)(750+4x) Hmmm. I get max revenue when x = -61. Sure those figures are right? Sure my function looks good?

MATH HELP!!!!!!!!
aside from the fact that I gave you the three numbers as the vector X, take a look at the 2nd url I gave you.

MATH HELP!!!!!!!!
well, since AX = B, X = A-1B X = 1/6 {23,2,29} The inverse is at{{+3%2C+2%2C+7}%2C+{+-2%2C+1%2C+4}%2C{+6%2C+-5%2C+8}}%29 and the solution is at{{+3%2C+2%2C+7}%2C+{+-2%2C+1%2C+4}%2C{...

Math Mixture Word Problem
the amount of saline must be the same before and after mixing: .05(1) + 0(x) = .02(1+x) .02x = .03 x = 1.5 check: 5% of 1L = .05L saline 2% of 2.5L = .05L saline or, you can say that since you want 2/5 the concentration, you need 5/2 the original volume, or 2.5L

algebra & trigonometry
well, just solve x^2 - 4000x + 7800000 = 3800000 x^2 - 4000x + 4000000 = 0 (x-2000)^2 = 0 x = 2000

the number is tu t > u u is in {2,4,8} t ≠ 2u t+u = is in {5,10,15} we know that t+u=10 because each is odd u≠8 because 9+2=10 and t>u u≠4 because 4+6=10 but t≠3k Looks like the number is 82

algebra & trigonometry
2*6+1 = ?

algebra & trigonometry
well, without knowing anything about f(x), I'd say you just have to solve 50 <= f(x) <= 80

7/x = cos60 = 1/2

what has a definite shape and volume a- solid b- liquid c- gas d- molecule My answer is A

if you mean 2 or less toppings the answer is 90. 95 minus the 5 with all 3 toppings.

looks like 14-8=6 to me

What did Antoine Lavoisier’s experiments demonstrate? a- Atoms always split into pairs during a chemical change. b- Mass is neither lost nor gained during a chemical change. c- Matter can be created during a chemical change. d- Energy is neither lost nor gained during a c...

Alg 2
well, 0 obviously works (2^4)^5/6 = 2^10/3 = 2^3*2^1/3 = 8*2^1/3 9(2^4)^7/12 = 9*2^7/3 = 36*2^1/3 14(2^4)^1/3 = 14*2^4/3 = 28*2^1/3 8=36-28 looks good to me You can check 7^4 in a similar manner.

which is a chemical property of aluminum a- melting point is 660c b- boiling point is 2519c c- does not dissolve in water d- reacts with oxygen My answer is D

what would happen to an object if the force of gravity on earth was decreased by half. a- its mass would decrease b- its weight would decrease c- its density would decrease d- its volume would decrease my answer is B

java programing
if (a>b) { if (b>c) {max=a} else {if (a>c) {max=a} else {max=c}} } else if (b<c) {max=c} else {max=b} } better check for balanced braces.

well, what is 1/4 + 1/4 ?

Algebra 2
#1 a) 1/4 * 1/4 b) 1/4 * 13/51 #2 a) 1/13 * 1/52 b) 1/13 * 1/51 #3 a) 3/13 * 1/13 b) 3/13 * 4/51 #4 a) 1/4 * 1/13 b) 1/4 * (4/51 + 3/51)

do we guess at what f(x) is?

algebra & trigonometry
20x+25y <= 1000 for a graphical solution, see

180mph = 3 mi/min using x,y,z coordinates, Stacey is at (-5,0,0) At time t minutes, The plane is at (0,3t,3tan15° t) = (0,3t,0.8t) So, at time t, the angle θ from Stacey to the point under the plane, is tanθ = 3t/5 So at 12 minutes, tanθ = 36/5 the angle of ...

Pre Algebra
that would be a square or a rectangle or a parallelogram. I guess you can figure out which to use, eh?

algebra & trigonometry
x+y+z = 7 y = 2z+1 x+z = y-2 x+y+z = 7 x-y+z = -2 2y = 9 y = 9/2 z = 7/4 x = 3/4

ball state
the slope is (4+2)/(6-3) = 2, so y-4 = 2(x-6)

If you want to know the number of whole tiles, then 11.5/1.2 = 9.6 9.5/1.2 = 7.9 So, assuming the cut pieces are not used, you will need 10x8 = 80 tiles

looks like you need to read about what a markup means A 40% markup means you add 40% to the price. So, if the price is $x, you wind up with x + 0.4x = x(1+.4) = 1.4x we don't need to carry around all those x's, we just need to know that the price after a 40% markup is ...

1.4*.75 = 1.05 so, a 5% final markup

Math Help
#1 I cannot see any way that equation will work with your answer. For if you are correct, 3x=17, and everything except the remaining x is an integer. No way to combine them in to 17/3.

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