Saturday
October 25, 2014

Posts by steve


Total # Posts: 26,094

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
42
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

Algebra
Is the following relation a function? ((0.3, 0.6). (0.4,0.8), (0.3,0.7), (0.5,0.5))
October 23, 2014

Math (Functions - Word Problem)
what's the trouble? Just sub in the values. Just watch that you change which definition of d(t) you use for the portions of the domain. year t d(t) 2000 0 10.6+0+699 = 699 2001 1 ... ... 2005 5 15.5*5+637 = 7145 2006 6 ... ...
October 23, 2014

trigonometry
If the tower has height h and is at a distance x, then h/x = tan 60° (h-6th)/x = tan 45° Eliminating h, we have x/tan 60° = x tan 45° + 6th x(1-1/√3) = 6th x = 6th/(1-1/√3) whatever 6th is supposed to mean.
October 23, 2014

Maths Question
since y'=0 at x=1,2,3,4,5 the max/min can occur there. But, y' has roots of even multiplicity at x=2 and 4, so those will be inflection points. So, extrema will occur at x=1,3,5 Why? The slope has to change sign at the extrema. If y' has roots of even multiplicity...
October 23, 2014

math
Well, since 7777-4444 = 3333 I've no idea. 7654-4567 = 3087 hmmm. still 90 off So, he must have done 7564-4567 = 2997 or 7654-4657 = 2997 So, he must have transposed two digits as shown above. That, as well as assuming that he could not repeat digits in the numbers.
October 23, 2014

Math
just plug in numbers for the letters a and s, and evaluate the expression.
October 23, 2014

algebra
How about x-3 + x + 2x+1 = 26
October 22, 2014

math
how long is the shelf? I don't feel like searching through all your posts to collect missing data.
October 22, 2014

math
how long is the shelf? You sure you want the thickness of a DVD case in feet?
October 22, 2014

geometry
v = 3.14 * 3^2 * 12
October 22, 2014

pre calc
Use your favorite quadratic regression calculator. I got P = 672.619t^2 - 7863.0952t + 64071.4286 but it's not a very good fit.
October 22, 2014

algebra
Look at the data, using just the changes (1600-760)af/(60-40)°F = 42 af/°F (2020-1600)af/(70-60)°F = 42 af/°F (2650-2020)af/(85-15)°F = 42 af/°F I guess that tells the story, eh?
October 22, 2014

math
3/4 + 1/9 find each sum
October 22, 2014

college algebra
C(t) = 14500 + 6.75t
October 22, 2014

Algebra Slope Intercept Form
or, just y = 1/5 x
October 22, 2014

Algebra Slope Intercept Form
correct
October 22, 2014

Calc
f(0) = 1+0 = 1 f(2pi) = 1+0 = 1 f'(x) = -sinx + 2sinx cosx = sinx(2cosx-1) So, f'=0 at x=0,pi,2pi and pi/3,5pi/3 f(pi/3) = 1/2 + 3/4 = 5/4 f(pi) = -1+0 = -1 f(5pi/3) = 1/2 + 3/4 = 5/4 Looks like the min is -1 and the max is 5/4 See http://www.wolframalpha.com/input/?i=...
October 22, 2014

arithmetic
If you want to find 8-0, recall that 8-8 = 0 so, 8-0 = 8 9-3? 9-6=3, so 9-3=6 Just google subtraction related facts, and study up some.
October 22, 2014

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