Wednesday
September 2, 2015

Posts by Steve


Total # Posts: 33,234

Biology
Of the following, which is the most likely consequence of a manufacturing plant dumping its chemical waste into a nearby stream? increased oxygen levels in the water decreased flow rate of the stream loss of a keystone species an algal bloom <- my answer My question is ...
September 2, 2015

PHYSICS
the crumpling bumper absorbs some of the impact, transmitting less force to the riders inside the car.
September 2, 2015

physics
The mass m does not matter. It takes about 1 second to fall 5 meters (using g=10m/s^2). Since v = at, that means v = 10 m/s
September 2, 2015

calculus
Looks like (a) to me. Assuming no typo in the equation.
September 2, 2015

Math
why bother with that? If the area is given in yd^2, just give each side in yd. √520 = 22.8035... So, each side is about 22.8 yd Now, if they wanted the dimensions in feet, then you'd divide the area by 9, since each yard is 3 ft, but you would certainly not divide ...
September 2, 2015

Math
If B's speed is x, the A's speed is x+53 Since distance = speed*time, we have 4.25(x + x+53) = 4568.75
September 2, 2015

AP Algebra
I also get 217.261 cm/s No idea what kind of rounding error produced 217.32 AAARFGBGGHH!! The Greek letter is pi</b not PIE! 4/3 π (4.6cm)^3 = 410 cm^3 Since mass = volume * density, that would be 410 cm^3 * 7.9 g/cm^3 = ...
September 1, 2015

Mystery number
Oh, wait. I misread the 2nd clue. It just means that both those digits are the same, since it said "value".
September 1, 2015

Mystery number
Just work through the instructions. I'll get you started, but I'm sure you can read as well as I. Start with xxx,xxx,xxx The digit in the tens place is the value of any number times zero. xxx,xxx,x0x The value of the hundred-thousands place is ten times the digit in ...
September 1, 2015

Geometry
(w+3)^2 = w(w+3)+54 w=15 So, the original rectangle was 15x18
September 1, 2015

math
c'mon -- that's just the difference of two squares, so you have (9-4x)(9+4x)
September 1, 2015

math
6x^3+14x^2-27x-63 2x^2(3x+7) - 9(3x+7) (2x^2-9)(3x+7)
September 1, 2015

math
well, just triple each dimension (11*3)(4*3) = (11*4)*3^2 since area involves two dimensions, it scales as the square of the linear dimension Perimeter, being just length, just uses the scale factor 2(3*11+3*4) = 3*2(11+4)
September 1, 2015

Math
h/83.2 = 5.8/2.5
September 1, 2015

Math
You just have to remember that dividing a number by itself gives a quotient of 1. When it says "solve for x" that means you want to find the value of x all by itself. SO, if you have -6g = 42 You just need to divide by the -6 to get g all by itself. Since -6g = 42, -...
September 1, 2015

Pre-Calculus
the roots are where g(x) = 0. So, you want 2x-5 = 0 x = 5/2 two lines are perpendicular if their slopes are negative reciprocals. That is, if line P has slope p, and line F has slope f, p*f = -1 Your first two answers are correct.
September 1, 2015

Math
math is ok, but intervals have the smaller value first. Also, you have a closed interval, since it's ≤ and not <. So your interval is [-2,-5/3]
September 1, 2015

Math
find t when 25 + 12t - 5t^2 = 3 using g=10 (easier than using 9.81)
September 1, 2015

math
The largest value is when x and y are almost equal: 10*11 The smallest value is when they are as different as possible: 1*20
September 1, 2015

Math
long piece is 6*7 other piece is 6*4 Maybe you can massage that into RDW.
September 1, 2015

math
what about that minus sign?
September 1, 2015

Algebra
x/y * y/x = 1 y*y*y*y*z = -16 x*y*y*z = 12
September 1, 2015

Math
both yes.
September 1, 2015

Math
wow. I suspect a typo. (1 1/10)/(1 1/5) = (11/10)/(12/10) = 11/12 So, you need 11/12 of 2 1/3 = 11/12 * 7/3 = 77/36 = 2 5/36 cups of milk. Mathematically precise, but not easy to measure. Luckily, 1/32 cup is 1/2 tbsp, so it can be done accurately.
September 1, 2015

Algebra
right on.
September 1, 2015

Algebra
generally, one says, "What is the product of x and y?" meaning x times y. A product, like a sum, needs two values. You give a single term, so I'd have said what is the value of (-6.8)^2 ?
September 1, 2015

Algebra
The math is correct. The grammar, not so much...
September 1, 2015

Maths
note that if the height is h, h*cot24° - h*cot38° = 300 Now just find h.
September 1, 2015

algebra
I'll assume you mean 1/(5/(x-1)+(3/x)) That would be x(x-1)/(8x-3)
September 1, 2015

Applied Maths 1
so, what about it? It's an interesting surface: http://www.wolframalpha.com/input/?i=1%2F%28sin%28x^2%2By^2%29%29^%281%2F5%29
September 1, 2015

algebra 2
Not sure any other version would be simpler, but if you want to get rid of the parentheses, (4xy^2)^-3 = 1/(4xy^2)^3 = 1 / 64x^3y^6
September 1, 2015

Maths
Let x = arctan(1/3) y = arctan(2/5) A+B = x A-B = y 2A = x+y tan2A = tan(x+y) = (tanx+tany)/(1-tanx*tany) = (1/3 + 2/5)/(1-(1/3)(2/5)) = 11/13 do 2B the same way
September 1, 2015

devi
or, if the "it" refers to the original amount, then 3/4 - 2/3 = 1/12 of the original amount on the dress.
September 1, 2015

devi
1/2 + 1/6 = 2/3 so, she spent 1/3 of the 3/4, or 1/4 of her original pocket money on the dress.
September 1, 2015

TC
Since sin(π-x) = sin(x), sin 7π/8 = sin π/8 sin 5π/8 = sin 3π/8 But your equation is clearly false, since all those sin^2 are positive, so they cannot add to zero.
September 1, 2015

math
the numbers are x and 2x+9, so x(2x+9) = 161 Now just solve for x. Or, note that 161 = 7*23, which fit the conditions above. You'd have had to figure that out to factor the quadratic anyway.
September 1, 2015

Maths
so, did you draw your diagram? Just start filling in the spaces.
September 1, 2015

math
y' = 1/x ds^2 = 1+y'^2 = 1 + 1/x^2 s = ∫[1,√8] √(1 + 1/x^2) dx wow - see what wolframalpha came up with: http://www.wolframalpha.com/input/?i=%E2%88%AB[1%2C%E2%88%9A8]+%E2%88%9A%281+%2B+1%2Fx^2%29+dx http://www.wolframalpha.com/input/?i=arc+length+ln%...
September 1, 2015

Math
as long as you came back, why did you not consult the related questions below?
August 31, 2015

8th grade math
9*6 = 54 beads used
August 31, 2015

Physics
3/2 the mass, 2/3 the acceleration.
August 31, 2015

Geometry
Assuming your math is ok as far as it went, have you not learned the quadratic formula? Use it, or solve by completing the square: x^2-x-14 = 0 x^2-x = 14 x^2 - x + 1/4 = 14 + 1/4 (x - 1/2)^2 = 57/4 x = 1/2 ±√(57/4) x = (1±√57)/2
August 31, 2015

Algebra
16/x
August 31, 2015

Math
22*4 + 15*6 - 3 - 134 = 41
August 31, 2015

Algebra 2
Looks like 5 hours to me. (2 hrs + 3 hrs) I suspect there is more to this question ...
August 31, 2015

Algebra 2
There is a nice elimination calculator online. It will show you all the details. http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
August 31, 2015

Math
let's use 13 numbers, so the median will be the center value. So, we start with x x x x x x 5 x x x x x x range and max: 2 x x x x x 5 x x x x x 8 mode 6: 2 x x x x x 5 6 6 6 6 7 8 others: 2 3 3 3 4 4 5 6 6 6 6 7 8 as long as there are more 6's than other values, ...
August 31, 2015

math
could be. You don't provide much context...
August 31, 2015

Calculus
d = 5t, so 6/s = 15/(5t+s) 6(5t+s) = 15s 30t = 9s s = 30/9 t
August 31, 2015

precalc
all are ok, except #5 should be y+4 = 2/3 (x+1) It makes a difference!
August 31, 2015

precalc
these are all point-slope problems. #3: y=4x-3 has slope 4, so your line has slope -1/4, and its equation will be y-1 = -1/4 (x-3)
August 31, 2015

Math
some negative numbers, like -3 and -1000 are integers. Others, like -2/3, -3.14 and -√7 are not
August 31, 2015

spanish
There's a tutoring web site called WyzAnt.com which helps find tutors in your area, in lots of different subjects.
August 31, 2015

Algebra
geez, guy. Can't you subtract 4 and check the result?
August 31, 2015

Algebra
Better go back to #3 and look again. The others look ok.
August 31, 2015

Math
Should show your work. Let the points (0,0), (2,1),(1,3) be A,B,C AB has slope 1/2 AC has slope 3 BC has slope -2 So, AB and BC are perpendicular. So, rotate the triangle about AB or BC AB is the line y = 1/2 x or x=2y BC is the line y = -2x+5 So, A is the correct answer. ...
August 31, 2015

Math
Find which two sides are perpendicular. Rotate the triangle about one of those sides.
August 31, 2015

Algebra
Let the smallest angle be x. Then, since the three angles add up to 180, x + (4x) + (4x-36) = 180 Now find x, and you can figure the angles.
August 31, 2015

Algebra-domain
x ∊ (-∞,-5)U(-5,6)U(6,+∞)
August 31, 2015

Geometry
you know the Pythagorean Theorem, right? The hypotenuse is the distance between A and B. The horizontal distance from A to B is (7-1) The vertical distance is (-7-1) Using the Pythagorean theorem, the length of the hypotenuse (the distance AB) is √((7-1)^2 + (-7-1)^2) = 10
August 31, 2015

math
try grouping: x^3-4x^2 -4x+16 x^2(x-4) - 4(x-4) (x^2-4)(x-4) (x-2)(x+2)(x-4)
August 31, 2015

Geometry-Help Please
use the edge to construct an arbitrary angle, with vertex at O. Mark an arc through the sides of the angle. Let the arc intersect the rays at A and B. Continue the arc on past B for a distance. Set the compass at B, and to the width of AB. Still with the compass at B, mark an ...
August 31, 2015

math(algebra)
since time = distance/speed, 40/(15+s) = 25/(15-s) Now just find s, the stream's speed.
August 31, 2015

Math
The area is 12(11+25)/2
August 31, 2015

math,accounts,economics
surely an accountant, eh?
August 31, 2015

Math
It's easier if you let u=4^x. Then 4^(x+1) = 4*4^x = 4u and you have u = 10-4u 5u=10 u=2 4^x = 2 but, 2 = √4 = 4^(1/2), so x = 1/2
August 31, 2015

Algebra
#1 is good #2 is also good, though I don't know why you added the "m" at the end. If you are trying to indicate units, then you should write $25 + $14/m * 6m so the "m" units cancel, leaving only $ In simple problems like this, it's usually easier ...
August 31, 2015

Algebra
#1 I finally figured how you got 169. Your strange symbol must have been this: 13[6^2÷5^2-4^2)+9] is indeed 169 which got garbled in my fonts. Try using / for division, as in 2/3. 2B 3D 4. Stop using x for times. Use * online, where x is usually used as a variable. Use ...
August 31, 2015

Algebra
#1 well, 13[6^2+9]=585 so if you are right, I have no idea what the €(5^2-4^2) means #2 B You correctly dived 6 by 2, so why not also cancel the xz in both top and bottom? #3 D He ended up with 78 after two losses, so you mustn't subtract them again. You need to ...
August 31, 2015

nahata high school
42
August 31, 2015

physics
they are on different tracks, or there is a break in the tracks between them. You mention no deceleration, so I must assume that their speeds do not change.
August 31, 2015

math
you want t where 2^(t/2) = 3 t/2 log2 = log3 t = log9/log2 = 3.17
August 31, 2015

additional
hmmm. don't know what "added" means? 4+x
August 31, 2015

math
not much to do, unless you want to just make it 4(2t^2+1)/t
August 31, 2015

Math
well, just plug it in. -0.623-194 ln (1-0.70) = 232.95
August 30, 2015

math
x^2*23y^2 = 1.78x10^32*z x^2 = (1.78x10^32 z)/(23y^2) x^2 = 7.739x10^30 z/y^2 x = 2.782x10^15 √z/y Ok. I'll take it as written (1.3*10^-4 x) = (4.7/x) - 6.3*10^-3 1.3*10^-4 x^2 = 4.7 - 6.3*10^-3 x 0.00013x^2 + 0.0063x - 4.7 = 0 x = -215.91, 167.45 I see you're ...
August 30, 2015

Math
true
August 30, 2015

algebra
√(h^2+30^2) = 2h+2 Looks like h=16 pretty puny tower...
August 30, 2015

math
6log_10 x=1.6 log_10 x = 1.6/6 x = 10^(1.6/6) = 1.848 e^(-4x) = 1.943 -4x = ln 1.943 x = (ln 1.943)/-4 = -0.166 OK. I'll take a stab at parsing this one: (1.3*10^-4) x = 4.7/(x - 6.3*10^-3) x(x - 6.3*10^-3) = 4.7/(1.3*10^-4) x^2 - 0.0063x - 36153.846 = 0 x = -190.138, 190....
August 30, 2015

Computer science
for n=1,3   print "name: ";read name   sum=0   for t=1,3     print "test     score #:,t     read s     sum += s   next t   avg = sum...
August 30, 2015

Math
For n hours, you want 800+16n = 720+21n Now just solve for n
August 30, 2015

math
greater than 20000 2xxxx first 2 & last digits are the same 22xx2 an odd number 33xx3 the middle digits are the same, 1 digit is twice the other digit 33663 But I suspect garbled language.
August 30, 2015

Algebra II
-2r^4 = 128 Can't be done, since r^4 is always positive. Now, 3 means between 2 and 128 are 4√2,16,32√2
August 30, 2015

Calculus
the radicand is a fraction, not a product. y = [(8x-x^6)/(x^3)]^(-4/5) y' = (-4/5)[(8x-x^6)/(x^3)]^(-9/5) * -(3x^5+16)/x^3 You can massage that to get the various forms shown here: http://www.wolframalpha.com/input/?i=derivative+[%288x-x^6%29%2F%28x^3%29]^%28-4%2F5%29
August 30, 2015

math
a+2d = 5 a+9d = 26 7d = 21, so d=3 and a = -1 A14 = -1+14*3 = 41
August 30, 2015

math
We may have taken different logs. Base 10 vs base e. Looks good to me. Does this fit any of the other data points very well?
August 30, 2015

math
if you know about exponents, you should know about logs, which are the inverse function. a^1000 = 1.096 1000 log(a) = log(1.096) a = log(1.096)/1000 = 0.0000917
August 30, 2015

math
huh? a^1 = 1 and a^-1 = 1/a, so 4 = ba 16 = b/a now divide: 4/16 = ba/(b/a) 1/4 = a^2 a = 1/2 so, b=8 f(x) = 8*2^-x
August 30, 2015

Math
A= ((r+z)/3)m A/m = (r+z)/3 3A/m = r+z 3A/m - z = r
August 30, 2015

trig
sec^4x=11tan^2x+5 (1+tan^2x)^2 = 11tan^2x+5 tan^4x + 2tan^2x + 1 - 11tan^2x - 5 = 0 tan^4x - 9tan^2x - 4 = 0 That's just a quadratic in tan^2x, so solve it, then just take the square root.
August 30, 2015

Math
recall that (a+b)(a-b) = a^2-b^2. So, you have (√37-√23)/(√37+√23) Now multiply by (√37-√23)/(√37-√23) and you have (√37-√23)(√37-√23) / (√37+√23)(√37-√23) = (37-2√37√23...
August 30, 2015

Math
a+m = 50 m-10 = 2(a-10) Now just solve for a and m.
August 30, 2015

Geometry
since 1L = 1000 cm^3, if the height ish, then we know that (20)(15)(h) = 4800 h = 16 So, the wet surface area is bottom + 2 long sides + 2 short sides = 20*15 + 2*16(20+15) = 1420 cm^2
August 30, 2015

equation
If you mean (9^x)^(-2) + (3^3)^x = 81 then you have 3^(-4x) + 3^(3x) = 81 if u = 3^x, then you have 1/u^4 + u^3 = 81 I'm sorry, but I don't see any algebraic solution. you sure there's no typo? Wolframalpha gets this: http://www.wolframalpha.com/input/?i=3^%28-4x%...
August 30, 2015

Math
well, divide x by 2 and then subtract 2 24/2 - 2 = 12-2 = 10 and so on for the others.
August 30, 2015

equation - eh?
Not sure what your parentheses mean. Multiplication, or more powers 9^x(-2) means -2*9^x or (9^x)^-2 = 9^(-2x) Why do you sometimes use ^ for powers, and other times not?
August 30, 2015

math calculus
0.5^(x/5730) = 0.95 x = 424 The 1815 date (195 years old) would still have 0.5^(195/5730) = 97.7%
August 30, 2015

math
just solve for t in (1/2)^(t/5730) = 0.95
August 29, 2015

Trigonometry/ please help!
you are correct. However, S=0 when t=1,3,5,7 That may have been what they intended to ask.
August 29, 2015

Calculus
(f'(π/3) = (-π/3 * √3/2 - 1/2)/(π/3)^2 = -(9π-3√3)/(2π^2) If we call that slope m, then the tangent line is y-1 = m(x-π/3)
August 29, 2015

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