Sunday

October 4, 2015
Total # Posts: 34,233

**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*

**alegbra 2**

Or, knowing that the equation of a parabola with focus at y=(0,0) and focus at y = -p is x^2 = 4py we have a shifted parabola with p=-3, so the equation is (x-6)^2 = 4(-3)(y-4) x^2-12x+36 = -12y+48 x^2-12x+84 = -12y Verify at http://www.wolframalpha.com/input/?i=parabola+%28x-...
*August 29, 2015*