Thursday

December 18, 2014

December 18, 2014

Total # Posts: 27,613

**Geometry**

You have to tell us what angles 1 and 2 are, in terms of the points A,B,C,D.
*October 26, 2014*

**Algebra**

since the domain of √u is u>=0, we need 2-x >= 0 That is, x <= 2 Next, we also need 1-√(2-x) >= 0, so √(2-x) <= 1 2-x <= 1 means x >= 1 -(2-x) <= 1 means x <= 3 So, we have a final domain of 1 <= x <= 2 The graph is at http://...
*October 26, 2014*

**Algebra**

the denominator cannot be zero. So, x^2+bx+8 must have no real roots. For that to happen, we need the discriminant to be negative: b^2-32 < 0 So |b| <= √32 5 is the greatest integer less than √32
*October 26, 2014*

**science (Need FAST FEEDBACK!!!)**

No idea. I'd have to google the terms. Oh, wait, you could have done that just as easily as asking here and waiting for a response.
*October 26, 2014*

**Math algebra**

for any radius r, the circumference C is C = 2πr So, just plug in the numbers you have for r
*October 26, 2014*

**math**

(4+x)(8+x) = 4*8 + 64 x^2+12x-64 = 0 (x-4)(x+16) = 0 x = 4 So, the rectangle is 8x12 with area 96 (32+64)
*October 26, 2014*

**MATHS**

If there were x 50-cent coins, x/6912 = 7/16 x = 3024 So, they collected 6912*.25 + 3024*.50 = $3240.00
*October 26, 2014*

**Calculus**

a square encloses the maximum area for a given perimeter.
*October 26, 2014*

**second degree equation word problem**

If there are now x rows, then each row has 720/x seats. The new configuration means that (x-4)(720/x + 6) = 720 (x-4)(6x+720) = 720x (x-4)(x+120) = 120x x^2-4x-480 = 0 (x+20)(x-24) = 0 ...
*October 25, 2014*

**Pre-calc**

cos(-7pi/6) = cos(7pi/6) = cos(pi+pi/6) = -cos(pi/6)
*October 25, 2014*

**math**

See http://www.wolframalpha.com/input/?i=f%3E%3D4 There's a number-line plot there.
*October 25, 2014*

**Precalculus**

using the law of cosines, the ship's distance x from the port is x^2 = 170^2 + 90^2 - 2*170*90 cos 14° Now just figure the coordinates of the ship and port to get the desired course. That assumes that there are no cross currents for the rest of the trip.
*October 25, 2014*

**Precalculus**

Hmm. Not having the diagram is a bit of a problem. In my diagram, extend the sea-level line TR to intersect PS at Q. Then, I have the angle of depression α = ∠PTR and β = ∠PQR. Apparently that is wrong, so please describe the diagram using only labeled ...
*October 25, 2014*

**Precalculus**

I don't see how ∠SPT can be 99°. ∠SPT = ∠SPR + ∠RPT = 51°+69° = 120° Did I miss something in the explanation?
*October 25, 2014*

**Pre-Calc/Trig**

you want two factors of 24 which add up to 10. List the factors: 1 2 3 4 6 8 12 24 Take them in pairs, working in from the ends. Note that 4 and 6 add up to 10, so you have (x+4)(x+6) = 0 x = -4 or -6
*October 25, 2014*

**Precalculus**

That is the angle between the vectors (7,10,0) and (7,0,3) So since (7,10,0)•(7,0,3) = √149√58 cosθ, cosθ = 49/√8642 = 0.527
*October 25, 2014*

**math**

f is increasing where f' is positive f' = 4-3x^2 So, where is 4-3x^2 > 0? similarly for decreasing. max/min where 4-3x^2 = 0
*October 25, 2014*

**math**

f' = (x+3) / 4x^(7/4) f' = 0 when x = -3. what about x=0?
*October 25, 2014*

**Math**

b = 3j m = 4(b+j) m = 4b+4j m = 4b+4(b/3) m = 16/3 b yes 3 = 1+2 3*8 = (1+2)*8 = 8+16 = 24 (12-4)*(2+1) = 8*3 = 24 12-4*2+1 = 12-8+1 = 5 in the absence of parens, multiplication is done before addition. That's why 3x+2 is (3*x)+2 and not 3*(x+2)
*October 25, 2014*

**math**

3*5 = 1/3 * x
*October 25, 2014*

**Algebra**

AB has slope 2/-6 = -1/3 So, (y+2)/(6-x) = -1/3 3y+6 = x-6 x=3y+12 So, pick any y and that will give you an x.
*October 25, 2014*

**Calc**

since v = 4/3 pi r^3 and a = 4 pi r^2, v = 1/3 ar so, dv/dt = 4pi r^2 dr/dt = a dr/dt so, dr/dt = (dv/dt)/a dv/dt = 1/3 (r da/dt + a dr/dt) = 1/3 (r da/dt + a*(dv/dt)/a) = 1/3 (r da/dt + dv/dt) = 1/2 r da/dt So, 10 = 1/2 (6.5) da/dt da/dt = 3.077 cm^2/s
*October 25, 2014*

**Maty**

3d+300m = 111 5d+600m = 198 Now just solve for d and m
*October 25, 2014*

**algebra**

check the related questions below
*October 25, 2014*

**Chemistry**

11.9g of am carb = 11.9/96.1 = 0.124 moles So, you get 0.248 moles of NH3 0.124 moles CO2 0.124 moles H2O Total moles of gas: 0.496 So, since 1 mole makes 22.4L at STP, adjust for your conditions.
*October 25, 2014*

**college algebra**

Using the point-slope form of the line, y-39000 = (64/39)(x-2000) So, when is y > 61000?
*October 25, 2014*

**Physics**

a = (36.6 m/s)/(8.22 s) = 4.45 m/s^2 F = ma
*October 24, 2014*

**Calc**

who cares about the volume? A = πd^2 dA/dt = 2πd dd/dt Now plug in your numbers to find dd/dt
*October 24, 2014*

**Secondary Math**

Hmmm. You have TR(-15x+3) = (-15x+3)(-2x+6) So, TopRight = -2x+6 BC = -3(-5x+1) = 15x-3 So, BottomCenter = 15x-3 That means BottomLeft = 2x-6 TopLeft = (-2x+6)/-3 = 2/3 x - 2 So, the filled-in square is (2/3 x - 2) (-3)(-2x+6) (3)(-5x+1)(-15x+3) (2x-6)(15x-3)(30x^2-96x+18)
*October 24, 2014*

**Algebra**

if the domain is all real numbers then the denominator can never be zero. That means it has no real roots. Thus, the discriminant is negative: b^2-32 < 0 So, if 0<=b<=5 x^2+bx+8 is never zero
*October 24, 2014*

**Physic**

a = 320km/hr / 6.5s * 1000m/1km * 1hr/3600s = 13.68 m/s^2 Since F = ma, the net force is 13.68m Since the net force is 1.52*10^4-5.2*10^3, divide that by a to get m.
*October 24, 2014*

**MATH HELP asap PLEASE**

the vectors to add are v = (550cos7°,550sin7°)+(85cos20°,85sin20°) so, plug in the numbers and get the sum. Then just get |v| and its direction
*October 24, 2014*

**math**

.4(6) = 2.4 = 24/10 = 12/5 or, .4 = 2/5, so .4(6) = (2/5)(6) = 12/5
*October 24, 2014*

**Math**

correct Though, to save us having to search back for your previous postings, it's better just to add a reply to them yourself. You can see where lots of posts have several replies.
*October 24, 2014*

**Algebra**

the denominator cannot be zero. So, its discriminant must be negative. That means 1-4c < 0
*October 24, 2014*

**Math**

Unfold the prism into a sheet, and draw a line from one point to the other. Then fold it back up again.
*October 24, 2014*

**math**

After Amy, .85 remained. After Beth, .80*.85 = .68 remained After Cathy, .88*.68 = .5984 remained So, 59.84% of the job remained undone. So, how did you arrive at 53%/ It's always good to show your work, so we can check to be sure your logic is correct.
*October 24, 2014*

**Algebra**

at x=1, r is undefined (∞) As x gets huge, r-> 0 The denominator is always positive, So, the range is (0,∞) See the graph at http://www.wolframalpha.com/input/?i=1%2F%281-x%29^2
*October 24, 2014*

**Calc**

A = πd^2 dA/dt = 2πd dd/dt Now plug in your numbers and solve for dd/dt
*October 24, 2014*

**algebra**

we want 23 + 1.75x < 7 + 3x Now just solve for x
*October 24, 2014*

**algebra**

that would be x miles, where 45.00+0.25x = 35.00+0.30x Now just solve for x
*October 24, 2014*

**Trig calc**

x = r cosθ y = r sinθ Now just plug in your numbers
*October 24, 2014*

**Trig**

x = r cosθ y = r sinθ Now just plug in your numbers
*October 24, 2014*

**Math Calc**

for any x, sin(x+180) = -sin(x) check the sum formula for sines
*October 24, 2014*

**Math**

f(-x) = -x^3+x^2+10x-24 2 sign changes, mean either 2 or 0 negative roots "A few" is not a very precise answer.
*October 24, 2014*

**Math**

1 sign change, so there is exactly 1 positive real root. The sign change is from +x^2 to -10x
*October 24, 2014*

**algebra**

2f-21 looks good to me. 2f is two times 2f-21 is 21 less than that. good work.
*October 24, 2014*

**math**

10+30*2.5
*October 24, 2014*

**Math Trig**

h/(120*3) = tan 40 now just evaluate
*October 24, 2014*

**Algebra**

we need |500m - 200t| <= 5 where m and t are the rates in $/minute
*October 24, 2014*

**math please help**

Not sure how the answer is 16 gallons. Better check my math.
*October 24, 2014*

**math please help**

from the Z table, 95% are below 1.645 std above the mean That means .39 + 1.645*.26 = .8177 So, there's a 95% chance that the average consumption is below .8177 gallons For 33 people , that means that there's a 95% chance that .8177*33 = 26.98 gallons will fed them all.
*October 24, 2014*

**maths**

a + ar = 28 ar^2 + ar^3 = 252 a(1+r) = 28 ar^2(1+r) = 252 ar^2(1+r)/a(1+r) = r^2 = 252/28 = 9 r = 3 or -3 a(1-3) = 28 ==> a = -14 a(1+3) = 28 ==> a = 7 So, now we need to know that ar^6 = 5103 7*3^6 = 5103 Unfortunately, that works whether r is 3 or -3 Using r = -3 7+(-...
*October 24, 2014*

**Algebra/math 117**

well, just count by 6's starting with a1=6: 6 12 18 ...
*October 24, 2014*

**Math**

half price is $2/ft^2 so, she paid 2*20 = $40
*October 24, 2014*

**Math**

Assuming one side of the run is 19.2, and is formed by the garage wall, then we have 2x+19.2 = 199.4 x = 90.1 ft That assumes also that the door to the run is contained in the garage wall, and thus no gate is needed in the fencing.
*October 24, 2014*

**Need Help asap for math!**

the vectors to add are (550cos7°,550sin7°)+(85cos20°,85sin20°)
*October 24, 2014*

**math**

12.45*24/1000
*October 24, 2014*

**Math**

Draw a diagram of a chord in a circle. In a circle of radius r, a chord of length 2x forms two right triangles where the distance d from the center is found using d^2+x^2 = r^2
*October 24, 2014*

**Trig calc**

figure r^2 = x^2+y^2 sin = y/r cos = x/r now just plug in the numbers.
*October 23, 2014*

**science**

the upper end. Think of a lever. less force has to be applied at the end, than near the fulcrum.
*October 23, 2014*

**math**

If I read it correctly, your dimensions are messed up. A 1x2 matrix * a 2x2 matrix yields a 1x2 matrix. How can y be 2x2? Take a look at this site, and you can enter your matrices using the sample notation. http://www.wolframalpha.com/input/?i=2{6%2C9}*{{27%2C-18}%2C{-12%2C15...
*October 23, 2014*

**Algebra**

That's what I get, too.
*October 23, 2014*

**Calculus please help**

dP/dR = 36 That is, if R changes by 1, P changes by 36.
*October 23, 2014*

**math**

A) x^2+y^3−xy^2=19 2x + 3y^2y' - y^2 - 2xyy' = 0 (3y^2-2xy)y' = y^2-2x y' = (y^2-2x)/(3y^2-2xy) B) Now just plug in the values C) see wolframalpha.com D) ...
*October 23, 2014*

**Science**

constant slope means constant speed. positive speed means increasing distance. So, which direction has the distance always increasing?
*October 23, 2014*

**Simple Physics**

solids have 3 dimensions planes have two dimensions lines have one dimension so, what do you think?
*October 23, 2014*

**calc**

Draw a diagram. When the water has depth y, its surface has width 40+(y/60)(100-40) = y+40 So, the volume of water when depth is y is v = y(40 + y+40)/2 * 7 = 280y + 7/2 y^2 so, dv/dt = 280 + 7y dy/dt Now just plug in your numbers Yeah, I know the units for v are in m-cm^2, ...
*October 23, 2014*

**algebra**

ok. what, you want a simpler numeric value for x? All those spaces are confusing, but if you mean log_3(5) * log_4(27) * log_3(√225) that is kinda weird. I suspect a typo. So, using base 3 logs all the way, I get log5*log27*log15 =4log3*2log5 since log_3(3) = 1, that is ...
*October 23, 2014*

**math**

If the dimensions are x and y, and assuming you want integer-length sides, the 2(x+y) = 18 x+y = 9 So, just start listing pairs of positive integers that add up to 9: 1 8 2 7 ...
*October 23, 2014*

**Algebra Slope Intercept Form**

y(0) = 6 so, y = mx+6 pick any two points to get the slope. For example, (0,6) and (2,0) the slope is -6/2 = -3 y = -3x+6
*October 23, 2014*

**math**

If the pieces are in the ratio 3:5 it means that if you divide the rope into 3+5=8 pieces, one part has 3 lengths, and the other has 5. So, since 40/8 = 5, the pieces have lengths 15 and 25 15:25 = 3:5
*October 23, 2014*

**Algebra**

Assuming you meant f(x) = 1/(1+(1+1/x)) excluded values occur when 1+1+1/x = 0 2+1/x = 0 x = -1/2 Well, that's probably wrong. How about f(x) = 1/(1+1/(1+1/x)) If 1+1/x = 0, then x = -1 1+1/(1+1/x)) = 0 if x = -1/2 So, now we have three values: 0,-1,-1/2 whose sum is -3/2
*October 23, 2014*

**ap calc**

if the bugs collide, then at some point B1 = B2. That means the distance between the bugs is zero, so B1-B2 = 0 (1/2 t^2-t+3)-(-1/4t^2+t+1)=0 3/4 t^2 - 2t + 2 = 0 Since the discriminant is negative, B1-B2 has no real roots. That is, it is never zero. So, the bugs do not ...
*October 23, 2014*

**ap calc**

Looks good to me.
*October 23, 2014*

**math Help!!!!!!**

We have a winner! But it's usually written a^2 + b^2 = c^2 The caret just indicates a power. In this case, the power is 2.
*October 23, 2014*

**math Help!!!!!!**

Surely you remember the 3-4-5 right triangle. Any of the choices look suspiciously similar?
*October 23, 2014*

**Trigonometry**

cos2θ = 1 - 2sin^2 θ so, 1 - 2sin^2 θ = 1/2 sinθ 4 sin^2θ + sinθ - 2 = 0 Now just use the quadratic formula to solve for sinθ, then take the arcsin. To check your answer, see http://www.wolframalpha.com/input/?i=cos2%CE%B8+%3D+1%2F2+sin%CE%B8
*October 23, 2014*

**geometry**

what is 448.92/12.77 ?
*October 23, 2014*

**math**

The smallest factor of x could be 2. So, the largest factor is at most x/2. There's a good chance that there's a prime between x/2 and x. So, start working backwards from x and checking the numbers for primality.
*October 23, 2014*

**Algebra**

Thank you
*October 23, 2014*

**Algebra**

f(n) =3 +4(n-1)
*October 23, 2014*

**Algebra**

What function represents the arithmetic sequence 3,7,11,15?
*October 23, 2014*

**Algebra**

q = kch^2 Now I guess you can probably solve for c.
*October 23, 2014*

**Calculus**

f is increasing where f' > 0 f' = 1/∛(x(64x^3-125))^2 Since (x(64x^3-125))^2 is always positive, f' is always positive, so f is always increasing. f is concave up when f" > 0 f" = (250-512x^3)/(2(64x^4 - 125x) ^(5/3)) So, f"=0 at x = &#...
*October 23, 2014*

**Math**

1/A + 1/B = 1/C 1/2 + 1/B = 1/1.25 Now just figure B.
*October 23, 2014*

**Int.science**

Assuming the rate was determined by observation, then since it involves measured numbers, it is quantitative Now, if the rate was calculated from physical properties, it'd probably be more theoretical.
*October 23, 2014*

**Math**

since all KE was converted to PE, 1/2 mv^2 = mgh v^2 = 2gh Now just plug in the numbers.
*October 23, 2014*

**Math**

First figure how many feet are needed, then divide that by 3 to get the yards needed. Then multiply by the price per yard: (10*11)/3 * 13.75 = $504.17
*October 23, 2014*

**Int.science**

Looks to me like uncertainty Can't see how size could depict the other characteristics. I can see where a large dot would indicate fuzzy precision, and a small dot would indicate greater accuracy.
*October 23, 2014*

**algebra**

just recall that y^a * y^b = y^(a+b) So, you have y^1/3 * y^4/9 - 3y^1/3 * y^2/9 = y^7/9 - 3y^5/9
*October 23, 2014*

**My Bad**

Oops. Don't know why I thought she had answered A. Sorry.
*October 23, 2014*

**celebrating Diversity**

excuse me? I see no mention of sex anywhere in the statement! It is clearly stereotyping.
*October 23, 2014*

**Algebra**

correct. You can easily check your results for yourself at wolframalpha.com
*October 23, 2014*

**physics**

what is a "4N point" ? and your cosine hints are mangled.
*October 23, 2014*

**Algebra**

What is the 9th term of the arithmetic sequence defined by the rule below? A(n)=-14+(n-1) (2)
*October 23, 2014*

**algebra**

note the slope from point to point: (2150-2200)/(20-15) = -50/5 = -10 (2050-2150)/(30-20) = -100/10 = -10 (1750-2050)/(60-30) = -300/30 = -10 So, it looks like F = -10T But, F(15) = 2200, not -150 SO, making that adjustment, we have F = 2350 - 10T
*October 23, 2014*

**Algebra**

Sound travels at 343 meters per second. How far does it travel in 8 seconds? My answer is 2,744 meters.
*October 23, 2014*

**Algebra**

Thank you -- I'm a gandparent trying to check my grandson's homework
*October 23, 2014*

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