Tuesday
January 27, 2015

Posts by steve


Total # Posts: 28,411

Math
h(t) = 75 + 80/√2 t - 16t^2 h=0 when t=4.563 The horizontal speed is a constant 80/√2 = 56.57 ft/s So, the ball travels 258.12 ft Hmm. We differ slightly. What did you do? And of course, check my math.
December 4, 2014

GEOMETRY
the area grows as the square of the radius. So, the radius grows as the square root of the area. Since areaB/areaA = 25, radiusB/radiusA = √25 = 5
December 4, 2014

algebra
domain: all real numbers except holes and vertical asymptotes vertical asymptotes where the denominator is zero and the numerator is not zero holes where the denominator and numerator are both zero horizontal asymptotes at the x-extremes. When x gets huge, you basically have f...
December 4, 2014

Coll Algebra
since time = distance/speed, we have d/(5-1) = d/(5+1) + 2 d = 24
December 4, 2014

5th grade math
Just do regular long division. In the quotient, place the decimal point directly above where it is in the dividend. Then move it to the right the number of decimal places as there are in the divisor. In normal long division with integers, the decimal point is at the right end ...
December 4, 2014

math
well, there are only a few perfect squares: 16 25 36 49 64 100 121 144 169 196 So, check the next numbers for primality. 17 is prime 26 is not and so on
December 4, 2014

Algebra 1
the slope is 2, so use the point-slope form to get y+3 = 2(x-1) or y-1 = 2(x-3)
December 4, 2014

Algebra 1
What is an equation in slope-intercept form for the line that passes through the point (1,-3) and (3,1)
December 4, 2014

chemistry
find the atomic wt of Ca figure the mol wt of CaCO3 So, the mass of Ca is just wt(Ca)/wt(CaCO3) * 1.229g
December 4, 2014

Chemiry 11
figure how many moles. Then, each mole contains Avogadro's Number of sulfur atoms.
December 4, 2014

Algebra 1
y = -2x so, k = -2
December 4, 2014

Algebra 1
For the equation -4y =8x, what is the constant of variation?
December 4, 2014

math
the given line has slope 5 So, you want a line with slope -1/5 That line is thus (recall the point-slope form): y-3 = -1/5 (x+10) and you can massage that into whatever form you like.
December 4, 2014

Calculus
I suspect a typo. Why write "1 sqrt(t)"?
December 4, 2014

Algebra
the distance s = 1/2 at^2 You have s and a, so just find t.
December 4, 2014

Algebra 1
thank you
December 4, 2014

Algebra 1
Suppose y varies directly with x and y = 24 when x =8. What is the value of y when x = 10?
December 4, 2014

algebra
The vertices involving y>=x are clearly (-2,-2) and (3,3) The rest you can surely find... What did you try? See the solutions at http://www.wolframalpha.com/input/?i=solve+x+%E2%89%A5+%E2%88%922%2C+x+%E2%89%A4+3%2C+y+%E2%89%A4+5%2C+y+%E2%89%A5+x+
December 4, 2014

math
what, no calculator? .01 is around 1/100, so the answer should be somewhere near 3 or 4
December 3, 2014

Math Help
The increase is 20 20/50 = 40% (of 50)
December 3, 2014

Math
Since √5 = 5^(1/2), log √5 = 1/2 log5 Not sure what all the other mumbo jumbo means.
December 3, 2014

Math
√(2-3x) = 9 2-3x = 81 3x = -79 x = -79/3 Remember: (a-bx)^2 is NOT NOT a^2 - b^2x^2 Not that that matters here, anyway, since √(stuff)^2 is just stuff, whatever stuff you have. (√x)^2 = √(x^2) = x. There is no reason at all to square what's inside ...
December 3, 2014

math
assuming the x side is parallel to the wall, then 2x+4y = 120 The area is 2xy = 2x(120-2x)/4 = 60x - x^2 The maximum area is thus where x=30 As usual with such problems, the maximum area is achieved when the fencing is divided equally among lengths and widths.
December 3, 2014

Algebra 1
What is an equation in slope-intercept form for the line that passes through the points (1,-3(), (3,1)?
December 3, 2014

Algebra 1
Thank you trying to help my grandson with his homework
December 3, 2014

Algebra 1
What is an equation for the line with slope 2/3 and y intercept 9?
December 3, 2014

Algebra 1
Suppose y varies directly with x and y = 24 when x =8. What is the value of y when x = 10?
December 3, 2014

Algebra 1
For the equation -4y =8x, what is the constant of variation?
December 3, 2014

Algebra 1
What is the slope of the line that runs through points (1,1), (0,3)?
December 3, 2014

Pre-Calc/Trig...
Since An/An-1 = r (1/An)/(1/An-1) = An-1/An = 1/r so, the ratio between terms is still constant.
December 3, 2014

College Algebra
If the amounts are x,y,z then we have x+y+z = 14000 .03x + .04y + .05z = 539 z = 3y Now just solve for x
December 3, 2014

Algebra 1
thank you
December 3, 2014

Algebra 1
the point 12,9 is included in a direct variation. what is the constant of variation
December 3, 2014

Algebra 1
Thank you, I'm a grandfather trying to help my grandson.
December 3, 2014

Algebra 1
suppose y varies directly with x and y = 14 when x = -4 what is the value of y when x = -6
December 3, 2014

Algebra 1
The ordered pairs 1,4 - 2,16 - 3,64 - 4,256 - 5, 1024 represents a function. What rule represents this function. 1- 4 x power 2- 4x 3- xto the 4th power 4- x+4 my answer is 4x
December 3, 2014

trig
zero. Why? try drawing the triangle...
December 3, 2014

maths
20
December 3, 2014

mathematics
If you mean 2 2/4, that's 10/4 1/4 / 1/4 = 10 yet, who actually writes 2 2/4 instead of 2 1/2? I suspect a typo. And lose the \\\'s. Try /// for fractions.
December 3, 2014

algebra
w*4w = 392 That gives you w. Now, you want p = 2(w + 4w)
December 3, 2014

AP CALC. AB
clearly the tangent is horizontal when x^2-2 = 0 h"(x) = (x^2+2)/x^2 And you know that f(x) is concave up when f"(x) > 0 See that graph at http://www.wolframalpha.com/input/?i=integral+x+-+2%2Fx
December 2, 2014

Calculas
Draw a diagram. If the man is x feet from the pole, and his shadow has length s, then using similar triangles, we see that s/6.5 = (x+s)/17 2s/13 = (x+s)/17 34s = 13x+13s 21s = 13x s = 13/21 x So, ds/dt = 13/21 dx/dt So, it does not matter how far away he is, his shadow's ...
December 2, 2014

algebra
3x^4 + 11x^3 = 4x^2 3x^4 + 11x^3 - 4x^2 = 0 x^2(3x^2+11x-4) = 0 x^2(3x-1)(x+4) = 0 ...
December 2, 2014

math
Between them, A and B cover 22-n miles on the nth day. You can see that this is an A.P. with a = 22 d = -1 So, we want to find Sn such that Sn = 165. So, n/2 (2*22+(n-1)(-1)) = 165 n = 9.2 So, on the 10th day they meet. n =
December 2, 2014

math
well, that would surely be 15/396
December 2, 2014

Math
0.8(4) + 0.8(-a) = 5.6a 3.2 - 0.8a = 5.6a 3.2 = 6.4a 0.5 = a
December 2, 2014

Calculas
You have x^2 + y^2 = 13^2 when x=5, y=12 2x dx/dt + 2y dy/dt = 0 Now plug in your numbers and solve for dy/dt.
December 2, 2014

calculus 2
well, just do 1 - cosθ = 1 + sinθ sinθ = -cosθ sin π/4 = cos π/4 So, in QII and QIV, sin 3π/4 = -cos 3π/4 sin 7π/4 = -cos 7π/4
December 2, 2014

geometry
Hint: the other side is 7.
December 2, 2014

Math
99
December 2, 2014

algebra
If tennis is x, then x + x+6.98 = 123.62 Now just find x and figure the other price.
December 2, 2014

Elementary Alegebra
j = 1.2s j-s = 5 Now just solve for j and s.
December 2, 2014

Earth Science
Which of the following statements correctly describes the asthenosphere? 1- it is thin cold and rigid layer 2- it is the source of the earth's heat 3- it permits plate motion 4- it occurs only near subduction zones My answer is 1
December 2, 2014

Math
√(49-25)
December 2, 2014

math
x^3 - y^3
December 2, 2014

Math help
Not quite -(-5-p) = 5+p so we have (5+p)^2
December 2, 2014

Business Math
Looks like it will be 7.35% of $720
December 2, 2014

coordinate algebra
hint: 3+4 = 7 3*4 = 12
December 2, 2014

math
why clutter things up with all the words? You clearly know how to write fractions. Benny: 4/10 Brother: 4/10 + 1/10 = 5/10 Sister: (1/2)(4/10) = 2/10 Assuming "him" again refers to Benny. (And it should be "he" anyway) Now add up the amounts.
December 2, 2014

MATH
Fe = 9/20 Beth = 2(9/20) = 18/20 Tina = 9/20 + 2/20 = 11/20 I think the questions can now be easily answered.
December 2, 2014

physics
step back, or throw the book really hard away from the table.
December 2, 2014

algebra
2(w + 3w-1) = 30 solve for w, and then figure the length
December 2, 2014

Algebra
-3/4 + 1/4 = -1/2 -9/10 + 2/5 = -1/2
December 2, 2014

algebra
116 - 6*8 = ?
December 2, 2014

language arts
Mine, too. Normally, the subjunctive is clearly indicated, as in So if you had any sense at all, you would avoid Storm Fever. (But, you clearly do not.) As phrased, it leaves open the possibility that you do have some sense, so based on that condition, you will avoid the movie.
December 1, 2014

algebra
well, just use what you're told. If the medium side is x, then x-7 + x + x+13 = 57 Now just find x and you're almost done.
December 1, 2014

MATH
7*5=35 2*4*35 = 280 (new area) 2(7*4+5*2) = 76 (new perimeter) 2(7*2+5*4) = 68 (new perimeter) You don't say which side is 2x and which is 4x larger No idea how to work this without double-digit numbers
December 1, 2014

Math
(97.65-45)/45 = ?
December 1, 2014

Newtons Law of Cooling
well, you know that dT/dt = k(68-T) dT/(68-T) = k dt ln(68-T) = kt + c1 68-T = e^(kt+c1) 68-T = ce^(kt) T = 68 - ce^(kt) We know that T(0) = 43, so c=25, and T = 68-45e^(kt) We know that T(12) = 55, so 55 = 68-45e^(12k) 45e^12k = 13 e^12k = (13/45) 12k = ln(13/45) k = ln(13/45...
December 1, 2014

calculus
You know that the average velocity is [y(3+h)-y(3)]/h So, just plug in the numbers and grind out the answers.
December 1, 2014

Algebra 1
use the vertical line test to determine if the relation(-6,-2), (-2,6),(0,3),(3,5) is a function
December 1, 2014

Algebra 1
What is the graph of the function rule? y=I5xI -2
December 1, 2014

Algebra 1
The ordered pairs(1,4), (2,16), (3,64), (4,256),(5,1024) represent a function. What is a rule that represents,this function? My answer is y=x to the 4th power
December 1, 2014

Algebra 1
The table shows the relationship between the number of players on a team and the minutes each player gets to play. Players minutes 7 35 8 30 9 25 10 20 Is the relationship a function that ism increasing or decreasing? Is the relationship a function that is linear or nonlinear...
December 1, 2014

Algebra 1
Write an equation that relates the number of parallelograms in the figure (n), to the perimeter of the figure (P). /_/ /_/_/ /_/_/_/ The top and bottom = 5 each and the sides = 4 each in each figure.
December 1, 2014

Rounding up and down
#1 0.34 #2 C 0.351 -> 0.4 0.562 -> 0.6 0.445 -> 0,4 #3 0.545 -> 0.55 Most people round up from 5. Some round to the closest even value, which would be 0.54 in this case. Follow the rules you were given.
December 1, 2014

math
treated in the related questions below.
December 1, 2014

Calculus
technically, since f(1) is not defined, you need to take the limits as x->1, but you will wind up with the same values.
December 1, 2014

Calculus
∫[-2,3] f(x) dx = ∫[-2,1] x dx + ∫[1,3] 1/x dx Now you can take it from there. Note that f(1) is not defined.
December 1, 2014

Calculus
well, which function is not constant?
December 1, 2014

Calculus
I assume you want the rectangles to have equal widths. Tat would be (5-1)/4 = 1. So, the left sides of the rectangles are at x = 1,2,3,4 the heights are f(1),f(2),f(3),f(4). So, evaluate f there and add up the areas.
December 1, 2014

Math
2(x+y) = 100 xy = 525 Carry on from there.
December 1, 2014

Trig
just recall your Pythagorean Theorem. It's also a distance formula.
December 1, 2014

Maths
This problem is discussed at http://www.beatthegmat.com/how-many-non-negative-integral-solutions-are-possible-t34635.html as you could have discovered with about 5 minutes' work.
December 1, 2014

Pleaaaaaase help with differential graph question
Sorry, no graphs here. But you know that since f(P) is dP/dt, when f is positive, P is increasing. As for the other items, no idea, since no picture is available. Sounds like P is some kind of exponential or logistic model. Better review those topics.
December 1, 2014

physics
8.0 rad / (2.56 rad/s) = 8.0/2.56 = 3.125 s Now convert that to minutes...
December 1, 2014

Maths
well, the first n terms of 2^(n-1) is 2^n - 1 The first n terms of 5n is 5 * n(n+1)/2 So, the sum you want is 2^n - 1 + 5n(n+1)/2
December 1, 2014

Maths
12 + 12+d + 12+2d = 6(1+r+r^2) But, d=r, so 36+3d = 6(1+d+d^2) 6d^2+3d-30 = 0 2d^2 + d - 10 = 0 (2d+5)(d-2) = 0 So, d=2 or -5/2 The two sequences are thus 12,14,16 6,12,24 with S3=42 or, 12,9.5,7 6,-15,75/2 with S3=28.5
December 1, 2014

Math
This is just an A.P. with a=4 d=4 The section in question has (64-4)/4 + 1 = 16 terms, so S16 = 16/2 (4+64) = 544
December 1, 2014

College Geometry
it's just a pyramid. And, of course Euler's formula holds.
December 1, 2014

movie
Hmmm. Try watching the movie! Failing that, if you are not familiar with America, just be aware that Tiffany & Co. is one of the most famous stores in the country. In particular, they sell fine jewelry and gifts.
December 1, 2014

Precalc/Trig
Suppose the nearer observer is at a distance x, and the tree has height h. Then, it is clear that h/x = tan30° h/(x+25) = tan20° Now, eliminate x and we see that h/tan30° = h/tan20° - 25 h(cot20°-cot30°) = 25 h = 25/(cot20°-cot30°) h = 24.62 ft
December 1, 2014

Physics
You can find the appropriate formula here: http://en.wikipedia.org/wiki/List_of_moments_of_inertia
December 1, 2014

math
The x- and y- changes from the first point to the last are 9 and 15 So, add 1/3 of those values to the first point.
December 1, 2014

Math
#1: 100000 * 1.1^5 #2: Sum of the first n integers is n(n+1)/2 #3 12 + 2*4/(1 - 1/3)
December 1, 2014

calculus
Oops. You are correct. So, make the fix and rerun the math.
November 30, 2014

calculus
The average rate of change between years a and b is (R(b)-R(a))/(b-a) Here, both intervals are 50 years, so things are convenient. You want to show that R(150)-R(100) ≈ 2(R(100)-R(50)) So, just plug in your numbers and see what you get.
November 30, 2014

Differential equations in Calculus...plsssss help?
so. you have dT/dt = -T/15 + 5 = -1/15 (T-75) dT/(T-75) = -1/15 dt ln(T-75) = -t/15 + k T-75 = e^(-t/15 + k) T-75 = ce^(-t/15) T = 75 + ce^(-t/15) Now, you are told that T(0) = 105, so 105 = 75 + ce^0 c = 30 T(t) = 75 + 30e^(-t/15) as desired in part (g) So, the coffee starts ...
November 30, 2014

Differential equations in Calculus...plsssss help?
Hard to see just what you wrote, but I'm guessing dT/dt = -1/(15T+5) (15T+5) dT = -dt No, that can't be right, if you want an exponential function. How about dT/dt = 15T+5 then we have dT/(3T+1) = 5dt ln(3T+1) = 5t+k 3T+1 = ce^5t T = (ce^5t - 1)/3 Hmm. Not that either...
November 30, 2014

Math
#1 You have an A.P. with a = 100 d = 50 S31 = 31/2(2*100 + 30*50) #2 You have a G.P. with a = 16 r = 1/4 So, find T7 and 2S6-16+T7 the strange sum is because you have just a drop on T1 and a bounce on T7, and not 7 complete round trips
November 30, 2014

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