Tuesday

February 9, 2016
Total # Posts: 37,527

**Math**

6*6*6*6 = 6^4
*January 13, 2016*

**Math**

if 100 is 35% of the price, then the original price is 100/.35 = $285.71 so, ...
*January 13, 2016*

**Math**

the depreciation factor is r, where r^6 = 2800/31000 = 0.090 The value after 3 years is thus 31000 * r^3 = 31000 * √.09 = 31000 * .3 = 9300
*January 13, 2016*

**Math**

There are 5! = 120 ways to arrange 5 subjects. Now, the 6th subject (which just happens to be one of the 5 as well) can be inserted in any place in the schedule. So, there are 6 places to insert it. The 6th subject can be any of the 5, so there are 5 ways to choose it. So, ...
*January 13, 2016*

**math**

come on, do some thinking. If a number is divisible by 5, it must end in 5 or 0. In this case, 5 must be the 3rd digit. That leaves 2,3,6,7,9 for the other two digits. So, there are 5 ways to pick the 1st digit. Once it has been picked, there are only 4 choices for the 2nd ...
*January 13, 2016*

**Algebra**

(a) no solutions. How can 4x-y be both -1 and -3? (b) many solutions: if you multiply the first equation by 2, you will see that both equations describe the same line. Google is your friend. Use it to get lots of examples of linear equations in problems. To solve by graphing, ...
*January 13, 2016*

**Math/Physics**

Draw a diagram. Review the definition of the cotangent. If the height is h, then h cot19° - h cot23.8° = 910
*January 13, 2016*

**Math**

what? eh? huh? Mark point T (the tee) Mark point H (the hole) Draw the line TH. Draw angle at T 21° from the line TH. Mark point (B) on that line roughly 3/5 as far from T as H is. Can you see the triangle?
*January 13, 2016*

**Geometry**

No idea, since you do not describe the figure.
*January 13, 2016*

**science help**

data is information. A is redundant. I'd say D.
*January 13, 2016*

**Math**

why can you not just say x/3 instead of the "over"? sheesh. -9p-17 = 10 -9p = 27 p = -3 x/3 - 10 = 12 x/3 = 22 x = 66 and so forth.
*January 13, 2016*

**Vector and scalar quantity**

3,5 - 4,3 = -0,8 so the resultant points to the left. I expect you can draw your own diagrams. Oh, wait -- maybe not, or you'd have seen the answer already...
*January 13, 2016*

**Math Correct Me!!**

The common multiple is 3, because 12*3 = 36 see http://www.phschool.com/iText/mgmath_course2/Ch05/05-04/PH_MSM2_ch05-04_Obj1.html and scroll down a bit. 4/5 = x/27 4*27 = 5x x = 108/5
*January 13, 2016*

**Algebra**

Try plotting the points. Note that (3,2) and (3,-9) form a vertical line of length 11 The point (2,-9) is one unit away, so you have a triangle with base 11 and height 1. Now, is that so hard?
*January 13, 2016*

**math**

.75x + 2 = .80x Now you can find x
*January 13, 2016*

**Maths**

After t hours, the distance d can be found by d^2 = 15t^2 + (5-10t)^2 2d dd/dt = 30t + 2(5-10t)(-10) 2d dd/dt = 230t-100 dd/dt = (230t-100)/(2d) since d is never zero, that means dd/dt=0 when t = 10/23 hours
*January 13, 2016*

**Mathematics, Vector, Physics**

come on. That's just 70 sin45° a wind from the southeast is blowing northwest
*January 13, 2016*

**Mathematics, Vector, Physics**

Let's see what I get h = 375.877i+136.808j w = -49.497i+49.497j so, v = 326.380i+186.305j = 375.810 @ 60.28° and those are headings, not bearings!
*January 13, 2016*

**Math**

Oops. that's 30θ = π
*January 13, 2016*

**Math**

s = rθ Plugging in your numbers, 60θ = π
*January 13, 2016*

**math**

I think you need to explain a bit more. Clearly the equation as written is false.
*January 13, 2016*

**math**

well, AB=15, so draw the triangle and it will be clear.
*January 13, 2016*

**Maths**

Do you mean r = -(1/2)^n?
*January 13, 2016*

**Algebra**

If their ages are x,y,z then we have z = y-4 y = 2z Clearly, Joe is 4 and Kyle is 8 so, ...
*January 13, 2016*

**Math**

9.96^2 = 99.2 in^2 24 ft^2 = 24*144 = 3456 in^2
*January 13, 2016*

**math**

If there is a common ratio, then you need (2x+4)/(6x+12) = (x-7)/(2x+4) x = 25 So, the common ratio is 54/162 = 1/3 Since |r| < 1, the sequence converges.
*January 12, 2016*

**algebra**

x^-2y = y/x^2 6z^-1 = 6/z If you want a single fraction, then that would be (yz+6x^2)/(x^2z)
*January 12, 2016*

**Calculus - Finally!**

1/2 log(u^2/(1-u^2)) 1/2 log(sin^2(x/2)/cos^2(x/2)) log(tan(x/2)) -log(cot(x/2)) -log((1+cosx)/sinx) -log(cscx+cotx)
*January 12, 2016*

**Calculus**

Well, I made a blunder, but you should have caught it. dx = 2/cos(x/2) du so, the integral becomes ∫ 1/2sin(x/2) * 1/cos(x/2) * 2/cos(x/2) du = ∫ 1/(u(1-u^2)) du = log(u) - (1/2)log(1-u^2) = (1/2)log((u^2/(1-u^2)) I feel that is headed somewhere we want. As usual, ...
*January 12, 2016*

**calculus**

dv/dt = 1.6t^3/√(0.2t^4+8100) Let u = 0.2t^4+8100 du = 0.8t^3 dt Now you have dv/dt = 2du/√u v(t) = 4√u + c = 4√(0.2t^4+8100) + c Now plug in your numbers to find c, and then find v(10).
*January 12, 2016*

**Math**

512 = 8^3 so the area is 6*8^2 Just to be precise, volume is not measured in cm^2.
*January 12, 2016*

**Math**

(n+2)^2 = 2n^2 - 1 You might think that it would be possible for n to be even, but since the right side must be odd, so must n^2 be odd, and thus any solutions you find will be odd.
*January 12, 2016*

**i need help**

that's one way.
*January 12, 2016*

**i need help**

d/12 = 24.5/7
*January 12, 2016*

**Algebra**

94 + x <= 110
*January 12, 2016*

**math help please**

since d = kf, d/f = k and is constant. So, you want d such that d/12 = 24.5/7
*January 12, 2016*

**Math**

the numbers are 1,5,9,... The nth white bead is bead number 4n-3
*January 12, 2016*

**math help**

10m = 1000 cm So, multiply the drawing dimensions by 1000.
*January 12, 2016*

**Calculus AB**

Maybe you have heard of Rolle's Theorem, a special case of the MVT.
*January 12, 2016*

**maths - incomplete**

depends on how much per ounce the 16-oz jar costs. Figure that out, subtract 5 cents, and then multiply that by 24 oz.
*January 12, 2016*

**Math**

which number has only two pairs of factors?
*January 12, 2016*

**Math**

#1. Nope. Add 7 to both sides #2. Nope. What is 5.5-4.5 again? #3. Nope. Subtract 12 from both sides #4. Nope. At least means not less than, right? Batting a big zero on this one.
*January 12, 2016*

**Algebra**

if the width is w, then the length is 200-w. (why?) the area is w(200-w). Can you take it from there?
*January 12, 2016*

**Math**

75 * 1.20 = 90
*January 12, 2016*

**Calculus**

800 @ 140° = <514,-613> 130 @ 27° = <59,116> So, you want <x,y> such that <x,y>+<59,116> = <514,-613> Once you have x and y, then convert back to speed and heading.
*January 12, 2016*

**maths**

it will float if its density is less than water's (1g/cm^3) so, figure your density and then answer the question.
*January 12, 2016*

**Math**

3x/3 = x so, ...
*January 12, 2016*

**math**

Since constants cannot intersect lines or parabolas in infinitely many points, and lines cannot intersect parabolas in more than two points, D is the only choice: the two expressions describe the same parabola.
*January 12, 2016*

**Geometry 1 question**

just use your distance formula. Or, the Pythagorean Theorem. Plot the points. The distance you want is just the hypotenuse of a right triangle with legs 8 and 3. So, it is √(8^2+3^2) Better study your material some more.
*January 12, 2016*

**MATH help**

B is exactly the opposite of true. The output depends on the input. Try C. Usually when making a table, you list the values of the independent variable, and then figure out the dependent values in column 2.
*January 12, 2016*

**Algebra help help!!!**

4^x-3^(x-1/2)=3^(x+1/2)-2^(2x-1) 4^x - 3^x/√3 = √3 3^x - 4^x/2 (3/2) 4^x = (√3+1/√3)3^x (3/2) 4^x = (4/√3) 3^x (4/3)^x = (8/√27) (4/3)^x = (4/3)^(3/2) x = 3/2
*January 12, 2016*

**PHYSICS**

there is no atom just free electrons which disperse or are attracted by some other charged particles
*January 12, 2016*

**Physics Component Method**

the components are (just as in polar coordinates): x = r cosθ y = r sinθ You have r and θ, so plug and chug.
*January 12, 2016*

**Shurley English**

true, but the words are preposition, noun, noun, conjunction, pronoun, verb, adjective, adjective, noun, preposition, noun.
*January 12, 2016*

**Algebra**

If there are x multiple-choice questions, then there are 15-x open ones. 4x + 12(15-x) = 100
*January 12, 2016*

**Calculus help!!!**

good luck with that! since e^u is always positive, you need y>0 and x>0 Since e^xy > 1, and grows very fast, I seriously doubt that x^2y will ever catch up, and sinxy is insignificant. Let y=0 or x=0 x^2y+sinxy=0 but e^xy=1 You can see that the slope of x^2y+sinxy is ...
*January 12, 2016*

**math**

b/g = 2/5, so 5b=2g g = b+9 Now just solve for b and g.
*January 12, 2016*

**Trigonometry - wow!**

Good luck with that! I have no clue how to get an exact solution. The graphs at wolframalpha.com and the analysis provided there don't give me much hope: http://www.wolframalpha.com/input/?i=2tanx+cos2x%2B1%3Dtan3x%2B2cos2x
*January 12, 2016*

**Homework for Math**

park area: 60*100 = 6000 If the terrace has uniform width w, then garden area is (60-2w)(100-2w) (60-2w)(100-2w) = 3000 Now just solve for w.
*January 12, 2016*

**Maths**

LCM(5,6,8) = 120 So, every 120 seconds they all fire together.
*January 12, 2016*

**Calculus**

Let x be the number of price decreases. Then the revenue is r(x) = (900-100x)(5000+1500x) = 100*500(9-x)(10+3x) = 50000(-3x^2+17x+90) Now find when dr/dx=0 and you can figure the price for maximum revenue.
*January 12, 2016*

**Calculus**

I'd say the critical point exists, since the usual definition that y'=0 or is undefined. In either case, I think that (3,0) is the critical point.
*January 12, 2016*

**calculus**

d/dx f^2 = 2f df/dx ∫ lnx/x dx Since we are discussing f^2, let's let f(x) = (lnx)^2 df/dx = 2 lnx * 1/x = 2lnx/x So, clearly, ∫lnx/x dx = (lnx)^2/2 + C check, using integration by parts: u = lnx dv = dx/x du = 1/x dx v = lnx ∫lnx/x dx = lnx*lnx - ∫...
*January 11, 2016*

**Calculus**

well, from the graph at http://www.wolframalpha.com/input/?i=+2+cos%28x%29+%2B+%28cos%28x%29%29^2 I'd say you were wrong. f = 2cosx + cos^2(x) f' = -2sinx - 2sinx cosx = -2sinx(1+cosx) f'=0 where sinx=0 or cosx = -1 x = 0 or pi
*January 11, 2016*

**Calculus**

1/2 ∫ 1/(sin(x/2)cos(x/2))dx let u = sin(x/2) du = 1/2 cos(x/2) dx or, dx = 2/cos(x/2) du Then you have 1/4 ∫1/u 2/(cos(x/2))dx = 1/4 ∫ 1/u du = 1/4 ln(sin(x/2)) + C Now, we all know that ∫ csc(x)dx = -ln(cscx + cotx) so what gives here? 1/4 ln(sin(x/2...
*January 11, 2016*

**Mathematics**

If there were x correct answers, then there were (120-x) incorrect answers. So, x - (120-x)/4 = 80
*January 11, 2016*

**math**

clearly the radius of the circle is 3. So, what is pi * 3^2 ?
*January 11, 2016*

**Math**

you know that tan(x) -> ∞ as x -> π/2 so, what do you think?
*January 11, 2016*

**math 1**

4":14' = 4":(14*12)" = 1:42
*January 11, 2016*

**math 1**

error was 10 10/85 = ?
*January 11, 2016*

**Math**

not differentiable if f'(x) is undefined. f'(x) = 1/√(1-x^2) so f' is undefined at x=±1 Now review the principal values of arcsin(x) cusps and corners are not differentiable, since the limit of f' is not the same from both sides.
*January 11, 2016*

**math**

since each triangle has sides 1/2 as big, the areas are 1/4 as big. So, just form a G.P. of the desired quantities and work with that.
*January 11, 2016*

**Math**

a+c = 9 8a+5c = 54
*January 11, 2016*

**Math**

Assuming you mean (5m^6)/(3n) that is just 5/3 m^6/n If the n is a typo, then you have 5/3 m^5
*January 11, 2016*

**math - eh?**

no idea what you're asking. Care to elaborate a bit?
*January 11, 2016*

**Math**

if you want 12, buy 10. If you want 26, buy 20 and that gives you 24, so then 2 more.
*January 11, 2016*

**MATHS**

just use the power rule and integrate each term separately. recall that ∫x^n dx = 1/(n+1) x^(n+1)
*January 11, 2016*

**math**

4n-3 <= 21
*January 11, 2016*

**Math (Help) thx!**

negative exponents move values from numerator to denominator and vice-versa. 7^-2 = 1/7^2 = 1/49
*January 11, 2016*

**Math**

(n+4)+n(n+2)+n=0 (n+4)+n(n+2+1)=0 (n+4)+n(n+3) = 0 n+4+n^2+3n = 0 n^2+4n+4 = 0 (n+2)^2 = 0 n = -2 or, n+2+2 + n(n+2) + n = 0 (n+2)+n(n+2) + n+2 = 0 2(n+2)+n(n+2) = 0 (n+2)(n+2) = 0 (n+2)^2 = 0
*January 11, 2016*

**Math log equation**

5^2x = (5^x)^2 So, make things easier to look at by letting u = 5^x Then you have u^2+20u-125 = 0 (u+25)(u-5) = 0 u = -25 or 5 But, 5^x is never negative, so we end up with u=5 5^x = 5 x = 1 check: 5^2 + 20*5 -125 = 25+100-125 = 0
*January 11, 2016*

**Math**

selling price will be 450000*1.03^10 Then just subtract the initial cost to get the profit.
*January 11, 2016*

**Math**

6 - (-2) C'mon, read your text.
*January 11, 2016*

**Math**

since the slope is constant, you need (n-4)/(6+2) = (4-1)/(-2-1) Now you can find n. Or, thinking about it another way, y increased by 3 when x decreased by 3. So, y will decrease by 8 if x increases by 8.
*January 11, 2016*

**Math log help**

Geez - give it a break, willya? Check your previous posts and be willing to wait a bit...
*January 11, 2016*

**Math**

Been there, done that http://www.jiskha.com/display.cgi?id=1452547715
*January 11, 2016*

**Math**

Not very patient, are ya? http://www.jiskha.com/display.cgi?id=1452547612
*January 11, 2016*

**Math logs**

Assuming the usual sloppiness with parentheses, we have 10^(3x-8) = 2^(5-x) (3x-8)log10 = (5-x)log2 (3log10)x - 8log10 = 5log2 - (log2)x x(log1000+log2) = 5log2+8log10 xlog2000 = log(32*10^8) x = log(32*10^8)/log(2000) x ≈ 2.88 Or, working a different way, 10^(3x-8) = 2...
*January 11, 2016*

**Algebra logs please help**

since 9 = 3^2, log3(n) = 2log9(n) That is, the power of 3 needed for a number is twice as big as the power of 9. So, we have 2log9(x) = log9(6x) log9(x^2) = log9(6x) x^2 = 6x x = 0 or 6 0 not allowed, so x=6
*January 11, 2016*

**Math**

#1 a 4x4 grid has 16 blocks Care to change your answer? #2 32% = 32/100 = 8/25 Care to change your answer? #3 6/24 = 1/4 Care to change your answer? #4 .09 = 9/100 Care to change your answer? #5 ok #6 4/9 = 0.44444... 11/25 = 44/100 That should clear things up #7 ok #8 9/15 = ...
*January 11, 2016*

**Math @angie**

your answer was easy to come by, but it did not answer the question. Also, 2/3 + 1/2 is NOT 3/5 Better review your fractions some before answering questions on them.
*January 11, 2016*

**Math**

correct. good job.
*January 11, 2016*

**Math**

did you actually try x=-6 to see whether you get the same y for both equations?
*January 11, 2016*

**Math**

well, if x=20, then y=70, since they add to 90. does 20 = 2*70-30? what did you do first?
*January 11, 2016*

**algebra**

15.99x <= 59.95
*January 11, 2016*

**@Studier2004**

42/6 is indeed 7, but it is not the answer to the question.
*January 11, 2016*

**math**

If the length is L, then 2(w+L) = 42 2(6+L) = 42 ...
*January 11, 2016*

**Math**

correct on all three.
*January 11, 2016*

**MATH HELP**

don't see any gold stars. You want to just write the question number, followed by your answers?
*January 11, 2016*

**Math**

correct.
*January 11, 2016*