Wednesday

November 26, 2014

November 26, 2014

Total # Posts: 27,016

**math**

original price for x radios is 1200/x So, (x-6)(1200/x + 10) = 1200
*November 6, 2014*

**math**

look at the multiples of 4 0 4 8 12 16 20 ... You can also consider that since the second number is 1 times the row number, then the row is 4.
*November 5, 2014*

**algebra help please**

well, just plug in the value for t: t=5: 2200 + (-480*5) = 2200-2400 = -200 and do the others the same way
*November 5, 2014*

**please help! algebra**

clearly there is no constant difference. Check for constant ratio (-12)(-5) = 60 (60)(-5) = -300 ... we have a winner. SO, what is 1500 * -5 ?
*November 5, 2014*

**Trig**

well, if you insist on using tan, then note that the base of the slide is √(250^2 - 107^2) = 225.9 cm out from spot directly under the slide's top. So, now we have tan θ = 107/225.9 = 0.47 θ = 25.3°
*November 5, 2014*

**Math, please help**

subtract the area of the painting from the total area. If the matte has width w, then (10+2w)(15+2w) - 10*15 = 10*15 4w^2 + 50w - 150 = 0 2(2w-5)(w+15) = 0 w = 5/2 = 2.5
*November 5, 2014*

**Math**

no way to tell the perimeter from just the area. All we know is that the smaller dimension is greater than 1.7 m.
*November 5, 2014*

**Help please Math**

No, what you want is a(bc) = (ab)c multiplication is associative. It is also distributive over addition: a(b+c) = ab + ac Of course, if a=1, a(bc) = (ab)(ac) because 1(bc) = (1a)(1b) = bc
*November 5, 2014*

**pre-algebra**

Nope. It triples every 4 hours, so in 24 hours it has tripled 6 times: x * 3*3*3*3*3*3 = x * 3^6
*November 5, 2014*

**chemistry**

since PV=kT, PV/T is a constant. So, using the given numbers, (.14 atm)V/(271+48) = (756 torr)(.295)/(271+18) You will need to reconcile atm and torr, and then solve for the new V
*November 5, 2014*

**Algebra**

not much of a scenario. They want a situation in real life which would produce such a decline and then increase in typing speed.
*November 5, 2014*

**geometry - incomplete**

how is point G defined?
*November 5, 2014*

**TRIG WORD PROBLEMS**

not sure just what you did, but if the height is x, then x/25 = tan 38° Actually, x is the shorter leg. The 38° angle is from the ground to the top of the building.
*November 4, 2014*

**Calculus- Please Help!**

Since moles is constant, nR is constant. SO, V dP/dt + P dV/dt = nR dT/dt You now have n = 2*6.02*10^23 P = 5 V = 15 dP/dt = -3 dV/dt = 0.6 So, plug in the numbers and solve for dT/dt
*November 4, 2014*

**English**

Thank you
*November 4, 2014*

**English**

In the Call of the Wild, Buck did not fight back when Hal was beating, him because? My answer is that he did not have the strengh
*November 4, 2014*

**English**

Thsnk you very much.
*November 4, 2014*

**English**

The hairy man represents what in the call of the wild? My answer is fear
*November 4, 2014*

**calculus**

v = ds/dt = 2/√(1+4t) a = dv/dt = -4/(1+4t)3/2 now just plug in t=6
*November 4, 2014*

**physics-distance**

r dθdt = .5 * 6.9 = 3.45 m/s is the linear speed. so, 3.45 m/s * 35*60 s = 7245 m
*November 4, 2014*

**Algebra 2**

(5+2w)(12+2w) - 5*12 = 168 Now just solve for w.
*November 4, 2014*

**Algebra**

that would be the plan. Should be pretty straightforward. One you get back to (1,1) you're done.
*November 4, 2014*

**math**

If there are v,w,x,y bike, trikes, tandems and unicycles, respectively, then we know v = 32 x=y Assuming all riders wear helmets, v+w+2x+y = 57 2v+3w+2x+y = 115 32 bikes 13 trikes 4 tandems 4 unicycles
*November 4, 2014*

**Math**

(x-2)^2 can never be negative. It is its minimum value of 0 when x=2. So, the vertex is at x=2. y(2) = -3, so the vertex is at (2,-3)
*November 4, 2014*

**algebra**

the slope must be 3, so now you have a point and a slope: y-2 = 3(x-0) y = 3x+2
*November 4, 2014*

**Math Gr 12**

OK. Now what? Hint: sin x = 1/1.25 = 0.8
*November 4, 2014*

**math**

the numbers are x,x+2,x+4 x + x+2 = (x+4)^2 - 201 Now just expand, collect terms, and solve the quadratic.
*November 4, 2014*

**calculus - unclear**

Seems like we need to know something about the production of bandages. Is it continuous? Instant batches of some fixed number? Production over a period of days? Is the consumption to be considered a continuous function? I see no way to solve this with the information given.
*November 4, 2014*

**Calculus please help me**

recall your second derivative concave up if f" > 0 inflection when f" = 0 concave down if f" < 0 So, you have f"(x) = 50x(x^2+75)/(x^2-25)^3 f" < 0 on (-∞,-5) f" > 0 on (-5,0) f"(0) = 0 f" < 0 on (0,5) f" > 0...
*November 4, 2014*

**Algebr**

just the way you would evaluate any complicated expression. Start deep and work outward: f^-1(5) = 13 f^-1(13) = 2 f^-1(1) = 5 So, you have f^-1((13+2)/5) =f^-1(3) = 1
*November 4, 2014*

**Math**

f decreasing means f' < 0 f' = 18x^2 - 126x - 144 = 18(x^2-7x-8) = 18(x+1)(x-8) Since that is a parabola which open upward, f' is negative between the roots. f(x) is decreasing on the interval (-1,8) This can be verified by looking at the graph: http://www....
*November 4, 2014*

**Algebra**

f(x) = (x+5)/3 f^-1(x) = 3x-5 g(x) = 1/(f^-1(x)+1) = 1/(3x-4) g(3) = 1/5 Of course, you might also have meant just what you typed, in which case g(x) = 1/f^-1(x) + 1 = 1/(3x-5) + 1 = (3x-4)/(3x-5) and so g(3) would be 5/4
*November 4, 2014*

**maths**

I'd say it depends on what is in the bag.
*November 4, 2014*

**Algebra 1 please help answer**

you have two conversion factors: $3 = 2 lb 1 apl = 5 oz So, to convert $ to lb, do $9 * 2lb/$3 = 18/3 = 6 lb 6lb * 16oz/lb * 1apl/5oz = 96/5 = 19.2 apples
*November 4, 2014*

**Algebra 1 please help**

7 gal * 25mi/gal = 175 mi
*November 4, 2014*

**algebra**

If A has a girls and B has b girls, then we are told: a-7 = b a+4 = 2b So, a=18 b=11 That means that A had 17 boys and B had 24 boys
*November 4, 2014*

**Algebra HELP!**

x in * 1m/39.37 in = x/39.37 m y = x/39.37
*November 4, 2014*

**Math**

#1 solve for x in x(1+.18/4)^(4*5) = 30000 #2 again, x(1+.045/2)^(2*15) = 50000 #3 100*(1/2)^(15/25)
*November 4, 2014*

**geometry**

Not sure what you mean by "rows" of wires. If you just need to find the perimeter of the rectangle, that is 2(0.7+0.5) km
*November 4, 2014*

**Calculus**

if g(x) = 1/√f(2x) dg/dx = (-1/2)f(2x)^-3/2 * f'(2x) * 2 so, g'(1) = (-1/2)f(2)^-3/2 * f'(2) * 2 = (-1/2)(5^-3/2)(-1)(2) = 1 / 5√5
*November 4, 2014*

**Calculus**

#1 f' = 3x^2-8x+5 f" = 6x-8 f is concave up when f" > 0 #2 f' = 6x^2-6x-6 maybe it cannot be factored, but since the discriminant is positive, it has real solutions. Use the quadratic formula to find them. #3 you want the slope to be 3. y' = 2e^x - 3 ...
*November 4, 2014*

**mathematics**

(y,z) = (5/2, -13/4)
*November 4, 2014*

**Calculus**

f' = 6x^2+9 clearly, f' is always positive, so there are no extrema, and no intervals where f is decreasing. Just think of what you know of the curve y=x^3
*November 4, 2014*

**Calculus**

the distance z is found using z^2 = u^2 + v^2 - 2uv cos 2pi/3 what are u and v? The girl's and boy's distances, where u = -6t v = 10t z^2 = 136t^2 - 60t^2 z^2 = 76t^2 so, now you know you have to find z(1/2), and then use z dz/dt = 152 t
*November 3, 2014*

**Math**

6*36 + 4*15 = ?
*November 3, 2014*

**Math**

48+64 + 2(48+64) = 336
*November 3, 2014*

**Algebra**

just evaluate as you would anyu other expression. work your way out from the inside: f^-1(3) = 4 (because they told you that f(4) = 3) So, now you want f^-1(4) That is 7, because f(7) = 4 The final answer is 7.
*November 3, 2014*

**math**

you want to spend less than $15 to buy three books. On average, the books must cost less than how much, each?
*November 3, 2014*

**Algebra**

f^-1(x) = (x-5)/4 So, f^-1(9) = 1 f^-1(1) = -1 So, no, the answer would be -1.
*November 3, 2014*

**Algebra**

No, you can't have h^-1 with both x and y in it. In fact, there are no x's here at all. Just interchange h and y and solve for the new h: y = (1+h)/(2-h) y(2-h) = (1+h) 2y - yh = 1+h h(1+y) = 2y-1 h = (2y-1)/(y+1) So, h^-1(y) = (2y-1)/(y+1) h^-1(5) = 9/6 = 3/2 check: h...
*November 3, 2014*

**Math**

rewrite as 3/9, 4/9, 5/9, ... 1/10, 4/10, ... 3/7, 4/7, 5/7 ... the 1st and 3rd are easy, but I'd have to pick 1/5 for (b) just because it's the only one with a 5 in the denominator. No idea on the pattern.
*November 3, 2014*

**Algebra**

Lots of problems posted, with no sign of effort on your part. No ideas at all?
*November 3, 2014*

**Algebra**

x = (3y-7)/(y+1) x(y+1) = 3y-7 xy + x = 3y - 7 y(x-3) = -(x+7) y = (7+x)/(3-x)
*November 3, 2014*

**Algebra**

E(t) is just a parabola. I'm sure you know how to find the vertex, where E is a maximum.
*November 3, 2014*

**Math**

4/9 * 36 = (4*4*9)/9 = 4*4 = 16
*November 3, 2014*

**Math**

If exactly 20, then it would be 8:12 So, since we have to add 5 marbles at a time (2+3=5), the next possibility is 10:15 makes 25 marbles
*November 3, 2014*

**math**

That depends - do the minutes roll over, or not? If not, then she had to buy 400 the 1st month 400 the 2nd month 600 the 3rd month That's $50+$50+$75 = $175 If they roll over at the end of the month, then she'd have to buy less in some cases.
*November 3, 2014*

**Algebra**

the max height is achieved at the vertex of the parabola, when t = 1 for (c), just solve 16t^2 - 32t - 240 = 0 16(t+3)(t-5) = 0 ...
*November 3, 2014*

**Pre-Calc**

90 days is 90/8.1 = 11.111 half-lives, so there would be 25*(1/2)^11.111 left
*November 3, 2014*

**Math**

well, -8 < -15/2 -3 < -3/2
*November 3, 2014*

**math**

2(x+y) = 25 xy = 32 x(25-2x)/2 = 32 25x-2x^2 = 64 2x^2-25x+64 = 0 x = 3.59 y=8.91
*November 3, 2014*

**Math**

m is undefined
*November 3, 2014*

**Math**

There are several ways to write the equation, depending on the information given: slope-intercept point-slope two-point x- and y-intercepts standard form general form So, read up on these topics, and you will learn several answers to your question
*November 3, 2014*

**Maths**

since 27 = 3*9, 3a-27 = 3a-3*9 = 3(a-9)
*November 3, 2014*

**mathematics Probability**

Since 2 is the only prime that is even, P(prime & even) = P(2) = 1/5
*November 3, 2014*

**Math**

raise 16 to the power on both sides. That gives 8 = 16^(3/4) take log base 3 on both sides 4 = log_3(81) This is because blogbN = N logbbN = N
*November 3, 2014*

**Math**

there is no other way. The roots are the zeroes are the x-intercepts. The quadratic formula always works. Use it when in trouble. Or, try and factor the polynomial x^2+8x+15 = 0 (x+3)(x+5) = 0 the roots are -3 and -5 Surely your algebra book covers the topic in several places.
*November 3, 2014*

**Math**

You must have access to some graphing utility. Here is a good one: http://www.wolframalpha.com/input/?i=-2%2F3+d^2+%2B+4d&a=*MC.d^2-_*Variable-&a=UnitClash_*d.*Days.dflt--
*November 3, 2014*

**Math**

The whole setup is bogus I'd go with (c), since it correctly notes that the solutions are -4 and 9. But -4+4 is (0), not (-8) If this is a proposed way to solve for zeroes, it's really stupid. x cannot be both -4 and 9 at the same time. Run far, run fast from this ...
*November 3, 2014*

**Algebra**

f(x) = 1/(ax+b) f^-1(x) = (1-bx)/(ax) So, we want 1+bx = 0 x = 1/b Or, if f^-1(x) = 0, f(0) = 1/b
*November 3, 2014*

**Math**

since h is the height above the water, it hits the water when h=0: -5t^2+10t+35 = 0 t = 1+2√2
*November 3, 2014*

**Calculus**

f' = -sinx-1 f'=0 at sinx = -1, so x = 3π/2 f" = -cosx, so f"(3π/2) = 0 Looks like an inflection point, not max or min. So, no extrema anywhere.
*November 3, 2014*

**algebra**

6p^2-2p+3 = 3 6p^2 - 2p = 0 2p(3p-1) = 0 p=0 or p = 1/3
*November 3, 2014*

**Trigonometry**

no idea whatcha got? Convert each length traveled to an x & y displacement. Then use the law of cosines to find the third length.
*November 3, 2014*

**Trigonometry**

Hmmm. The 72 feet is measured on the slope, not out from the pole horizontally. I get top of pole is at 40 + 72 sin17° downhill point is 72 cos 17° from point beneath the pole cable^2 = (40+72 sin17°)^2 + (72 cos 17°)^2
*November 3, 2014*

**Trigonometry**

As usual, draw a diagram. It is clear that if the nearer student is x away from the spot under the balloon, then h/x = tan 28° h/(x+7) = tan 15° Eliminate x and you have h/tan28° = h/tan15° - 7 Now just solve for h
*November 3, 2014*

**algebra**

a#3 = a^2/3 = 9 a^2 = 27 ...
*November 3, 2014*

**Algebra**

f^-1(x) = (x+8)/3 So, we want (x+8)/3 = 3x-8 x+8 = 9x-24 8x = 32 x = 4 3*4-8 = 4 (4+8)/3 = 4 Note that the same results could have been achieved by setting f(x) = x 3x-8 = x 2x = 8 x = 4 Why? because f(f^-1) = x by definition. So, if f^-1(x) = f(x), then f^-1(f) = f^-1(x) x = ...
*November 3, 2014*

**Math**

elimination, or matrix inverse?
*November 3, 2014*

**math**

Well, as long as I'm clarifying :-) :-) :-) That would be 45 seconds, not .45 seconds Or, if you insist on decimals, try .75 minutes!
*November 3, 2014*

**math**

Not quite. After 12 minutes he has climbed 12 meters In the 13th minute, he climbs the final 3 meters and is done. Final time is thus 12:45
*November 3, 2014*

**calculus**

since x^2+y^2 = 36 x dx/dt + y dy/dt = 0 since we want dy/dt = -dx/dt, (x-y) dx/dt = 0 true when x=y, as might be expected. Or, when x = 6/√2 All that stuff about 4m and .5 m/s is just noise, unless there are other parts to the problem.
*November 3, 2014*

**Pre calculus**

r = 7/(5+4sinθ) r(5+4sinθ) = 7 5r + 4rsinθ = 7 5r = 7 - 4y 25r^2 = (7-4y)^2 25x^2 + 25y^2 = 49 - 56y + 16y^2 25x^2 + 9y^2 + 56y = 49 25x^2 + 9(y+28/9)^2 = 49 + 9(28/9)^2 25x^2 + 9(y+28/9)^2 = 1225/9 x^2/9 + (y+28/9)^2/25 = (7/9)^2 See http://www.wolframalpha.com...
*November 3, 2014*

**Calculus**

f(x) = 5x√(x+2) is continuous and differentiable on [0,2], so the MVT applies. f(2) = 20 f(0) = 0 So, the slope of the secant is 10 MVT says that f'(c) = 20 somewhere in [0,2] f'(x) = 5(3x+4) / 2√(x+2) f'(c) = 0 if 5(3c+4) / 2√(c+2) = 10 5(3c+4...
*November 3, 2014*

**math**

If the airport is at (0,0) first leg is to (-2.819,1.026) the second leg is on a course of S20°W for a distance of x where 1.026-xcos20° = 0 x = 1.092 So, the 2nd leg is to (-3.192,0)
*November 3, 2014*

**Algebra**

I'm sure that by now you have figured out that I made an error: (u^2+1 - u^2) / u(u-1) 1 / u(u-1) Now set that equal to 1/u 1 / u(u-1) = 1/u 1 = u-1 u = 2 check: 5/2 - 2/1 = 1/2
*November 2, 2014*

**Algebra**

I assume you mean (u^2+1)/(u^2-u) - u/(u-1) Clearly the LCD is u(u-1) (u^2+1 - u(u+1)) / u(u-1) (-u+1) / u(u-1) Now put both sides over the LCD, throw out u=0,1 and set the numerators equal. Then solve for u. What do you get?
*November 2, 2014*

**Algebra**

If the savings account pays x%, then (x+10)/x = 65/15 x = 3 check: .03m = 1500 m = 50000 So, $50K was invested .13(50000) = 6500
*November 2, 2014*

**Algebra 2**

there are 10 digits; only 8 allowed to start, so 8*10^6
*November 2, 2014*

**Algebra check?**

all correct good work. You can also check your answers by typing in the expression at wolframalpha.com
*November 2, 2014*

**Algebra**

If you're trying to find the expression for the area, you have for some reason combined the x^2 and x terms (a no-no). The area is 1/2(2x^2+4x+2)(x^2+3x-4) (x+1)^2 (x+4)(x-1) As you say, not sure which way to go. You have an expression for the area. Was there some other ...
*November 2, 2014*

**algebra**

huh. That's quite a question just to drop in. Have you not studied your algebra text? The basic idea is that if an equation is true, it remains true if you apply identical operations on both sides of the equal sign. The goal is to choose the operations in an order which ...
*November 2, 2014*

**Math**

You are correct to feel ill at ease. You have confused area and perimeter. You want (x+7)(6) = 120
*November 2, 2014*

**algebra**

After x miles, you want 8 - x/30 = 12 - x/18
*November 2, 2014*

**Calculus I**

If by optimal age, you mean producing the maximum offspring, then yes, you want to find where dr/dx = 0 r(x) = log(e^-.1x * 4x^1.5)/x That's kind of messy, and not tractable to algebraic solution. Netter use a graphical or numeric method. Looks like dr/dx=0 at x=1.07875 ...
*November 2, 2014*

**Algebra**

√7 (7-√7) + 9√7 7√7 - √7√7 + 9√7 16√7 - 7
*November 2, 2014*

**Algebra 1B**

You may be more familiar with the term "discriminant." The discriminant is b^2-4ac, the value inside the square root symbol. So, in this case, the surd being considered is the square root of the discriminant.
*November 2, 2014*

**Math (I've been on this problem for 3 hours)**

well, as I recall, the equilibrium price and quantity are where supply equals demand. So, we want 2p-q+10 = (p+q)(q+10)-3642 since q = 2p+10, that means (p+2p+10)(2p+10+10) = 3642 6p^2+80p-3442 = 0 p = 18.195 so, q = 46.390 Check: 2(18.195)-46.390 +10 = 0 (18.195+46.390)(56....
*November 2, 2014*

**Math (I've been on this problem for 3 hours)**

If the supply and demand functions for a commodity are given by 2p - q + 10 = 0 and (p + q)(q + 10) = 3642 respectively, find the equilibrium price and quantity that give market equilibrium. (Round your answers to two decimal places.) Equilibrium price =
*November 2, 2014*

**physics**

then it hits a brick wall, and bursts into flame. How much energy is released by the explosion of the fuel tank?
*November 2, 2014*

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