Thursday
August 25, 2016

Posts by STEVE

Total # Posts: 42,758

Math
as shown earlier, 3log_2(-x-6)
July 14, 2016

MATH
log_a(3) = log_b(27) log_a(3) = 3log_b(3) log_a(3)/log_b(3) = 3 log_b(a) = 3 b = a^3
July 14, 2016

Math
log_2(x) has asymptote at x=0, so log_2(x+6) has its asymptote at x=-6 But, its domain is x > -6. So, we want log_2(-x-6) at x = -8, we have log_2(8-6) = 1 So, we want y = 3log_2(-x-6)
July 14, 2016

Math(help please)
all we know is that 1/25 of the items are red pens. Assuming an integer number of items, that makes C the only reasonable choice.
July 14, 2016

Math
sorry - no pictures here. Surely you can draw a reasonable picture of lines a and b. Let a be the x-axis Then b is the line y=x (45°) Now, line c will be parallel to the y-axis. So, you now have a right triangle with two 45° angles.
July 14, 2016

MATH
or, to avoid introducing a new base, f^-1(x) = log1/3x = -log3x log and exponentiation are inverses, just like + and - * and / square root and square We just don't have any special symbols to denote the operation.
July 14, 2016

mathematics
These would be all the multiples of 24.
July 14, 2016

Math
u.v = 5*3*cosπ/3 = 15 * 1/2 = ?
July 14, 2016

pre cal
just plug in your numbers: cosθ = u•v ----------------------- |u| |u|
July 14, 2016

math
70^2 + 120^2 + 2*70*120 cosθ = 90^2 cosθ = -2/3 θ = 131.8° This makes sense, since if the two forces were separated by an acute angle, the resultant would be greater than either of them. Think of the parallelogram involved.
July 14, 2016

Math
not sure what that is, but it is the graph of log_3(x) reflected through the y-axis shifted right by 3 stretched vertically by a factor of 2 shifted down by 2 Note that log_3(-3x+9) = log_3(3) + log_3(3-x) = 1 + log_3(3-x) This cancels the scale factor on the x-axis by ...
July 14, 2016

Chemistry
well, 12g C + 32g O2 → 44g CO2 ?? If all 18g of C were used, there would be only 66g CO2. Am I missing something here?
July 14, 2016

algebra
it will take t hours, where 1.039^t = 2
July 14, 2016

Math
you want y(0) = 5, so log3(k^2)-1 = 5 log3(k^2) = 6 k^2 = 3^6 k = 27
July 14, 2016

Science
write the balanced equation convert grams to moles find the limiting reagent see how many moles of it will be used see how many moles of H2O will result convert back to grams
July 14, 2016

Maths
The factors of 6262 are 1x6262 2x3131 31x202 62x101 The first two are out, since there's no room for the blue border and red interior. So now, check the others and pick the one which allows for more red tiles. 29x200 60x99
July 14, 2016

physics
since the speed is uniform, its average is 30km/h
July 14, 2016

maths
rather than from 2:00 to 11:00, I read it as moving from, say 12:10 to 12:55, or 9/12 of an hour.
July 14, 2016

math
the number is between 3500 and 4500 So, now we start working with the info. The hundreds digit is even, so 363x 384x 400x 421x 442x If the digits add to 12, that means we can have only 3630 4008 4215 4422 So, what do you think?
July 14, 2016

math
as with all boxes, it is length * width * height = 21√5 * 12√3 * 25√3 = 18900√5
July 14, 2016

Math
That's what I get.
July 14, 2016

Math
that will be h(10)-h(9)
July 14, 2016

algebra
As we know, h(x) = a+bx-16x^2 a+b-16 = 148 4a+2b-64 = 272 solve that and you end up with h(x) = 4 + 160x - 16x^2 ...
July 14, 2016

Math
since 1/4 = 6/24, use that ratio for all the numbers. Then you have 1/6 : 1/8 : 1/4 1/6 - 1/8 = 1/24 Or, 4-3 = 1 Now scale that and you get 1/24
July 13, 2016

algebra
slope = distance/time
July 13, 2016

Math (PLEASE HELP!)
since cos(t) has a max at t=0, and we want the passenger to start at the bottom, a will be negative. r=13, so h(t) = -13cos(bt)+d h(0) = 1, so h(t) = -13cos(bt)+14 The period is 24, so h(t) = -13cos(π/12 t)+14
July 13, 2016

maths
Clearly you were having trouble, as you posted no work of your own.
July 13, 2016

maths
Clearly the floor is 0.1m thick. So, multiply the volume by the unit cost, and you get a cost of (7*3 + 6*2)(0.1)(65) = ?
July 13, 2016

math
since distance = speed * time 4(s-20) = 3(s+20) and we know what airspeed: it's its speed in the air. (note apostrophe)
July 13, 2016

maths114
The area of the minor segment is 1/2 r^2 (θ-sinθ) So, plug in your values and subtract that from the area of the circle, πr^2
July 13, 2016

Math
If they lost x games, then we have x + 3x+15 = 95
July 13, 2016

maths 114
area of circle minus area of minor segment.
July 13, 2016

math
(x-1)y" + 2y' = 0 If we expand about x=0, we assume y = ∑anx^n y' = ∑nanx^(n-1) y" = ∑n(n-1)nx^(n-2) Plug these into our DE and we have (x-1)∑n(n-1)nx^(n-2) + 2∑nanx^(n-1) = 0 ∑n(n-1)nx^(n-1) - ∑n(n-1)nx^(n-2) + 2&#...
July 13, 2016

Math
well, since 3 = 18/6, the cost is X/6
July 13, 2016

math
well 64πh = 384π
July 13, 2016

maths
6cis 5π/6 * 3cis 4π/5 = 6*3 cos(5π/6 + 4π/5) = 18 cis 49π/30
July 13, 2016

analytic geometry
since (8,0) divides the line into a proportion, (8-x)/(10-x) = (0-7)/(y-7) y = 14/(x-8) There are many possible lines. A few possibilities are x=9, y=14 x=10, y=7 x=15, y=2 x=22, y=1 x = -6, y = -1 x = 1, y = -2 x = 6, y = -7 x = 7, y = -14
July 13, 2016

math
t = 2-x, so y = 1+2(2-x) = 5-2x At t=0, we have (2,1)
July 13, 2016

Math
If x is the original number, x/24 = x-16 Comes out a fraction. If, on the other hand, you meant to say he got a quotient which was 16 less than the correct quotient, then we have x/24 = x/12 - 16 x = 384 I suspect you have garbled the question.
July 13, 2016

Maths - duh
Stupid me. I read the question as "two equal parts" and wondered what the fuss was about. Clearly the ratio would be 1:1 Nice catch, Reiny.
July 13, 2016

Maths
what do you mean by "their areas"?
July 13, 2016

math
it has to make up 130 miles in 3 hours. So, its speed is 65 + 130/3 mi/hr
July 13, 2016

pre-calculus
well, for 30° it is (1/2, √3/2) Now move that around 180°
July 13, 2016

computer sc.
no diagrams, but the steps are n=50 i=0 sum=0 get score i += 1 sum += score i<n? If so, repeat avg = sum/n
July 13, 2016

Pre Calculus
or, more directly, using deMoivre: 8cis10 * 5cis200 = 8*5 cis(10+200) ...
July 13, 2016

math
just plug in the numbers where F = 9/5 C + 32
July 13, 2016

math
speed = distance/time, so 1.4km/1.667hr = 0.84 km/hr or, using fractions, (7/5)km/(5/3)hr = 21/25 km/hr
July 13, 2016

Algebra
6/20 --------- = 2/5 3/4
July 12, 2016

Math
y = a(x+3)(x+1)(x-4) at x = -2, (x+3)(x+1)(x-4) = 18 so, y = 4/3 (x+3)(x+1)(x-4)
July 12, 2016

Pre-Cal
Draw your triangles in standard position. Then it is clear that sinx = -4/5 tanx = 4/3 cosy = -√77/9 tany = -2/√77 Now just plug the needed values into the identities you have
July 12, 2016

Pre-Cal (Help Please!!!!)
#1 cosθ (3tan^2θ - 1) = 0 so, cosθ = 0 or tanθ = ±1/√3 Those are standard familiar values, right? #2 tan3θ = -1 3θ = 3π/4 or 7π/4 + n*π/3
July 12, 2016

Math
Just factor as usual: 2x + 9√x - 5 = 0 (2√x-1)(√x+5) = 0 √x = 1/2 x = 1/5 √x = -5 no solution there
July 12, 2016

Algebra
just expand and equate coefficients 4x^2+20x+r = 4x^2+4sx+s^2 4s=20 s=5 r = s^2 = 25 r-s = 20
July 12, 2016

Physics
F = ma, so a = F/m = 18N/6kg = 3 m/s^2 v = at = 3*5 Now you try the other. Same ideas.
July 12, 2016

maths studying for pre cal test
draw angle A and side b. Now, if it were a right triangle, with b the hypotenuse, side a would be the altitude, of length 14 sin60° = 12.12 So, you see, a little side a of length 4 will not reach down the the base, AB. If C is the right angle, that means that tanA = 6/14, ...
July 12, 2016

Studying for math test
Read the question carefully. It said which of the following is not equivalent? Actually, both c & d are not
July 12, 2016

Studying for math test
take a look at the related questions below. In particular, http://www.jiskha.com/display.cgi?id=1468255540
July 12, 2016

12th grade chemistry
normalbold
July 12, 2016

12th grade chemistry
<pre> abc def ghi jkl </pre>
July 12, 2016

12th grade chemistry
<font size="4">size 4</font> <font size="2">size 2</font>
July 12, 2016

12th grade chemistry
abc<small>abc</small>
July 12, 2016

science
well, p = mv plug in your numbers and solve for v.
July 12, 2016

chemistry
note that each 2 moles of KOH produce 1 mole of Mg(OH)2. So, how many grams in 2 moles of magnesium hydroxide?
July 12, 2016

MATHS
42°
July 12, 2016

MATHS
3x+A=45 x = (45-A)/3 Is there something else you want to specify?
July 12, 2016

Math
or, differentiating y' directly, y" = 50y^3(-5xy^2+20xy+18)/(10xy+9)^3 y"(1,1) = 50(-5+20+18)/19^3 = 1650/6859 which agrees with Reiny's result above!!!
July 12, 2016

physics
How long does it take the bomb to fall 8000m? 4.9t^2 = 8000, so t=40 s In 40s, the bomb will travel 8000m. What a coinkidink! So, the angle is just 45°
July 12, 2016

math
just solve 3x + 1/2 x^2 = 8
July 12, 2016

pre cal
splashdown occurs when h=0 max height is at t = -b/2a = 115/9.8
July 12, 2016

agebra
well, if you know the mean and the std, µ-2σ <= x <= µ+2σ
July 12, 2016

math
dy/dx = xy dy = xy dx dy = 1*2 * 0.4 = 0.8
July 12, 2016

pre cal
recall that the vertex of a parabola is at t = -b/2a so evaluate h(t) there.
July 12, 2016

maths
Just change the numbers in Reiny's solution here: http://www.jiskha.com/display.cgi?id=1455402753
July 12, 2016

pre cal
well, the diagonal of the square is the diameter of the circle...
July 12, 2016

pre cal
The time it takes for the sound to come back is d/c The time it takes to fall a distance of d is found using h0 + v0 t - g/2 t^2 = d Solve that for t, and then you have t = 1/g (v0 + √(v0^2 - 2g(d-h0))) Now you know that 1/g (v0 + √(v0^2 - 2g(d-h0))) + d/c = t Now ...
July 11, 2016

Algebra/Calculus
note that (x+y)^2 = x^2+2xy+y^2 x^3 + y^3 = (x+y)(x^2-xy+y^2) Now just plug in what you know.
July 11, 2016

algebra 2
3x-15 = 0 when x=5 everything else is ok.
July 11, 2016

algebra 2
a denominator cannot be zero because division by zero is undefined. For this one, 64 is never zero.
July 11, 2016

Pre-Cal
recall that tan(x+y) = (tanx + tany)/(1-tanx*tany) so, cot(x+y) = (1 - tanx tany)/(tanx + tany) Now divide top and bottom by tanx*tany sinx(cotx+tanx) = sinx(cosx/sinx + sinx/cosx) = cosx + sin^2x/cosx = (cos^2x + sin^2x)/cosx = secx
July 11, 2016

algebra
ok
July 11, 2016

MATH
As I said earlier, e^(a+b) = e^a * e^b That means that e^(a+b+c) = e^a * e^b * e^c Now just plug in your values for a,b,c.
July 11, 2016

Pre-Cal
Looks ok to me. It might be easier to read π/6 + nπ 5π/6 + nπ So, plug in various values of n to get all the solutions in [0,2π) There will be four of them
July 11, 2016

math please help?! studying for test!!
√(81+x^2) = √(81+81tan^2θ) = √(81(1+tan^2θ)) = √(81sec^2θ) = 9secθ Looks like you need to brush up on your basic trig identities.
July 11, 2016

math help?!
36-x^2 = 36-36sin^2θ = 36(1-sin^2θ) = 36cos^2θ so, √(36-x^2) = 6cosθ
July 11, 2016

Pre-Cal (Help Plz!)
so, you got tanθ = ±√3 cosθ = -1/2 tanθ = √3 means θ = π/3 or 4π/3 tanθ = -√3 means θ = 2π/3 or 5π/3 cosθ = -1/2 means θ = 2π/3 or 4π/3 so, that gives nπ + π/3 nπ + 2...
July 11, 2016

Pre Calculus
Hmmm. I get cosu*cosv - sinu*sinv = (-24/25)(-12/13)-(7/25)(5/13) = 288/325 - 35/325 = 253/325
July 11, 2016

Pre Calculus
since y>0 and x<0, draw your triangles, and you can see that cos u = -24/25 sin v = 5/13 Now just plug them into your cos(u+v) formula.
July 11, 2016

MATH
yes, as far as you went. But, if you are using natural logs, log(e) = 1, so the answer is just 5y By definition logbb^n = n b^(logbn) = n because logs and powers are inverse functions, just like √x and x^2 are inverses. Like + and - or * and / It's just that we don&#...
July 11, 2016

MATH
recall that e^(a+b) = e^a * e^b AND LOSE THAT CAPS!!
July 11, 2016

maths
"square bracket"? Is your keyboard defective, so you can't just type "[" ? Even more confusing is that you didn't use what I gave you at http://www.jiskha.com/display.cgi?id=1468255629
July 11, 2016

Pre-Cal
you know that the reference angle is θ = π/3, right? Because cos π/3 = 1/2 Now, since cosπ = x/r, you need x negative, so you are in QII and QIII. So, draw your triangle on the negative x-axis, giving you π-π/3 and π+π/3 = 2π/3 and ...
July 11, 2016

Analytic geometry
Using what I gave you here: http://www.jiskha.com/display.cgi?id=1468252134 you can surely figure the rest, no? Heck, I even showed you the graph! Where do you get stuck?
July 11, 2016

math
Not unless 7-1 = 8
July 11, 2016

Math
If what you have is 0.5(x-2)^2 ------------------- (x+1)(x-5)^3 then you have 0.5(x^2+...) / (x^4+...) which approaches zero for large values of x.
July 11, 2016

pre calculus
No. You are half right. θ=12x is the right substitution to use, but if θ = 12x, what you have is cos(θ/2) = cos 6x
July 11, 2016

pre calculus
did you even look up your half-angle formula? It says that cos(θ/2) = √[(1+cosθ)/2] I think the substitution is now clear.
July 11, 2016

maths
recall that 2 sin x/2 cos x/2, so the equation becomes cos x/2 - 2 sin x/2 cos x/2 = 0 cos x/2 (1 - 2sin x/2) = 0 I think you can handle that, right?
July 11, 2016

math
but a triangular pyramid does: v = 1/3 Bh Now just plug in your numbers.
July 11, 2016

maths
you telling me or asking me? Naturally, sin(2x) is not one of your answers, but if you let x = π/10 and you plug that in, I bet it is one of your answers.
July 11, 2016

maths - Oops
Dang! That is sin(2x) = 2 sinx cosx
July 11, 2016

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