Tuesday

January 27, 2015

January 27, 2015

Total # Posts: 28,393

**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*

**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*

**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*

**Math**

If there are x correct and y incorrect, then we have x+y=10 5x-2y = 29 Now just solve for x.
*November 30, 2014*

**Calculus**

That is correct. So, the limit is +∞, since the denominator near x=1 is always positive.
*November 30, 2014*

**Math please help!**

A glass of skim milk supplies 0.1 mg of iron, 8.5 g of protein, and 1 g of carbohydrates. A quarter pound of lean red meat provides 3.4 mg of iron, 22 g of protein, and 20 g of carbohydrates. Two slices of whole-grain bread supply 2.2 mg of iron, 10 g of protein, and 12 g of ...
*November 30, 2014*

**AP calc**

well we need the limit from both sides to be the same. f(2) = 2^2+3*2-1 = 9 So, we need -3bx+3 = 9 when x=2 -3b*2+3 = 9 -6b = 6 b = -1
*November 30, 2014*

**physics**

When a 1.50 kg block is 3.96 m above the base of the hill, the mass has a speed of 1.71 m/s. When the block reaches a point 0.750 m above the base of the hill, what is its kinetic energy?
*November 30, 2014*

**AB Calculus**

(a) is correct. Not sure how the sand maintains a constant plane cross-section, but we'll posit that. The volume of the conical pile is v = 1/3 π r^2 h If we assume that the aspect ratio of the cone does not change, then r = 8/23 h, so dr/dt = 8/23 dh/dt dr/dt = 3/4 ...
*November 30, 2014*

**ap calc**

and besides, everyone knows that for large values of 2, 2+2=5, for small values of 5.
*November 30, 2014*

**ap calc**

depends on the operator "+" and the base of the number system.
*November 30, 2014*

**geometry**

Just use what yo know about the interior and exterior angles. If there are n sides, you want 180(n-2)/n = 360/n + 100 180n-360 = 360 + 100n 80n = 720 n = 9 check: 180*7/9 = 40+100
*November 30, 2014*

**calc**

∫∫S f(x,y,z) dS we have f(x,y,z) = y z = 2/3 (x^3/2 + y^3/2) ∂z/∂x = x^1/2 ∂z/∂y = y^1/2 so the integral becomes ∫[0,5]∫[0,2] y √(x+y+1) dy dx Looks pretty straightforward now, right?
*November 30, 2014*

**Calculus**

Hmmm. -1/3 - 1 = -4/3 I get (B)
*November 30, 2014*

**AP Calculus**

Just use the quotient rule: h' = (f'g - fg')/g^2 = (14*1 - 0*1/7)/1^2 = 14
*November 30, 2014*

**Calculus**

the slope is 3/2, so y-3 = 3/2 (x-1) 2y-6 = 3x-3 3x-2y+3 = 0 Looks like (A) to me
*November 30, 2014*

**math**

9P5 = 9*8*7*6*5
*November 30, 2014*

**Calculus (Cross Section) again**

consider the stick as a stack of very thin slices of radius √(3x) and thickness dx. Apparently the whole stick is to be considered. v = 2∫[0,10] πr^2 dx where r^2 = 3x. So, v = 2∫[0,10] π(3x) dx v = 6π∫[0,10] x dx I think you can probably...
*November 30, 2014*

**Calculus (cross section)**

since the area of a triangle is 1/2 base * height, if the base is 2y, then we need only double the volume of half the solid, due to symmetry. v = 2∫[0,6] (1/2)(2√(36-x^2))(4) dx = 8∫[0,6] √(36-x^2) dx Now just plug and chug.
*November 30, 2014*

**Math**

Robyn: M=2d Shruti: M=3+d Since Shruti adds a constant 3 miles to her multiple of d, her relationship is not strictly multiplicative.
*November 30, 2014*

**percentages**

1.12*1.14 = 1.2768, or 27.68% change Doesn't matter how tall it was to start with, since we are given the changes as percentages.
*November 30, 2014*

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