Friday

July 29, 2016
Total # Posts: 42,162

**Psychological Stats**

you can play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html
*June 23, 2016*

**MATH**

10^-4 million = 10^-4 * 10^6 = 100
*June 23, 2016*

**math**

#1 because (x-y)^2 = (y-x)^2 why don't you try the others? Just remember that (z)^2 = (-z)^2
*June 23, 2016*

**maths**

xy = 5/6 x/y = 15/8 6xy = 5 8x/15 = y 6x(8x/15) = 5 48x^2 = 75 x^2 = 75/48 = 25/16 x = 5/4 y = 2/3
*June 23, 2016*

**Algebra**

If there are w,x,y,z pizzas of the sizes, then we have 100w+144x+196y+256z = 300*256 z >= 150 y > x 40 <= w <= 50 You have said nothing about how much they need to make from the sales, so the price information is just noise.
*June 23, 2016*

**Calculus**

for a cube of side s, v = s^3 dv/dt = 3s^2 ds/dt Thus, ds/dt = 2/15 mm/s a = 6s^2 so da/dt = 12s ds/dt da/dt = 16 mm^2/s
*June 23, 2016*

**Algebra**

assuming simple interest, 2500*7*r/12 = 19.76 r = .0135, or 1.35%
*June 23, 2016*

**Algebra**

Jack bought x/3 - 10
*June 22, 2016*

**Algerbra**

There are none. All accounted for by the equation.
*June 22, 2016*

**Math**

7, since there are 7 apples. I suspect you have omitted something.
*June 22, 2016*

**Math (exam tomorrow)**

In that case, just look at the graph. It is clear that cos(x) is steepest where it crosses the x-axis. Without calculus, I can't think of an analytical test to prove where the slope is steepest. Are there any similar problems in your text?
*June 22, 2016*

**Math (exam tomorrow)**

the slope is given by the derivative f(x) is increasing fastest where the slope is steepest. That is, the derivative has a maximum. Take a look at the graphs of f and f' and you will see that for this problem, f is increasing fastest when x = 3π/4 http://www....
*June 22, 2016*

**math**

No way to tell. All we know is that wxy is isosceles, and wx < 38
*June 22, 2016*

**Math**

What you have is 4 d^4 w^3 * 6 d w^4 ---------------------------- 3 d^3 w * 8 d w^2 collecting powers of each variable, that is 24 d^5 w^7 ----------------- 24 d^4 w^3 I think you can see what cancels out now, right?
*June 22, 2016*

**math**

If you mean 4(2^(x^2)) = 8^x 2^2 * 2^(x^2) = (2^3)^x 2^(2+x^2) = 2^(3x) 2+x^2 = 3x I'm sure you can do that. Next time you post one of these, try showing some of your work first, ok?
*June 22, 2016*

**Maths**

I can't parse your words. Try using math symbols instead. Something like x((3 * 1/5)+(3 * 1/10)) = 9/10 or something. You've mangled the values and operators.
*June 22, 2016*

**math**

If the base has side x, then x^2 + 4x(x+1) = 96
*June 22, 2016*

**math**

NO, YOU DO NOT When you divide 345 by 145 you get 2.3 You are doing it backwards! By hand, you need to start out with 345)125 345 is the divisor, not the dividend!
*June 22, 2016*

**math**

you are dividing backwards: 345/145 = 2.3
*June 22, 2016*

**Math**

To figure the height after 1 minute, h/150 = tan 28°29' Now, having h, you know that 3h is the altitude after 3 minutes. So, find the angle θ such that tanθ = 3h/150 Or, in one step, θ = arctan(3*150*tan28°29')
*June 22, 2016*

**MATH ARITHMETIC SEQUENCES**

I assume you meant 1,1.1,1.2,... Tn = 0.9 + 0.1n So, to find which term is 3, 0.9 + 0.1n = 3 0.1n = 2.1 n = 21 So, T21 = 3 Makes sense. Every 10 terms another 1.0 is added: T1 = 1 T11 = 2 T21 = 3 T31 = 4 ...
*June 22, 2016*

**Science**

google is your friend. Just type in the left side of the equation and you will get many hits showing the balanced result.
*June 22, 2016*

**Math**

If the 100 is in base 2 or 5, then 100*100*100 = 1000000 regardless of base
*June 22, 2016*

**maths**

just add 180°
*June 22, 2016*

**math**

If we're allowing decimals, then I'd say the smallest is 0.123456789 If not, then I'd have to go with 1,023,456,789
*June 22, 2016*

**math**

Since 13.5 = 3*4.5, 3 times as much zinc is also used.
*June 22, 2016*

**math**

since 8 = 2^3, you have 2^2 * 2^x = 2^(3x) 2^(2+x) = 2^(3x) 2+x = 3x x = 1 check: 4(2^1) = 8^1 4*2 = 8 yep
*June 22, 2016*

**math**

just type your rational function in at wolframalpha.com Be sure to use parentheses. It will show how it interprets your input.
*June 22, 2016*

**maths**

suppose that there is a number x such that 0/0 = x Now, clearing the denominator, we have 0 = 0*x but that is true for any x, so 0/0 is undefined.
*June 21, 2016*

**Math**

or, if you really do want grams, figure how many grams of dextrose are in 100ml of the solution
*June 21, 2016*

**geometry**

I think you left out some coordinates. However, E is clearly 1/4 of the way from C to D.
*June 21, 2016*

**CALC**

dy/dx=−4xe^(y−x^2) dy/dx = -4xe^y e^(-x^2) -e^-y dy = 4x e^(-x^2) e^-y = c-2e^(-x^2) y = -ln(c - 2e^(-x^2)) since y(1) = 11, -ln(c-2e^-1) = 11 c - 2e^-1 = e^-11 c = 2e^-1 + e^-11
*June 21, 2016*

**math**

add up all the fares and divide by how many days.
*June 21, 2016*

**Math/Conversions**

Your answer is how much was left, not how much she drank. Read the question carefully...
*June 21, 2016*

**Algebra**

x/5 - g = a x/5 = a+g x = 5(a+g)
*June 21, 2016*

**PHYSICS**

F=ma the tension in the string is the downward weight of the 2kg mass. The force on the 3kg mass is that weight.
*June 21, 2016*

**math**

Draw a diagram. If the chord has length 2x, then x/200 = sin 34°
*June 21, 2016*

**maths**

That would be 8(1+2+3+...+14+15) You can find the sum of the first n numbers, right?
*June 21, 2016*

**maths**

using the law of cosines, AC^2 = 96^2 + 80^2 - 2*96*80 cos56°
*June 21, 2016*

**math**

3/8
*June 21, 2016*

**math**

1/5 * 3/4
*June 21, 2016*

**Maths**

20m^2 * 1.5m * 1000L/m^3 ---------------------------- = 600 min 50 L/min
*June 21, 2016*

**CALCULUS**

The graph should make things clear: http://www.wolframalpha.com/input/?i=%7Cx%5E2%2F2-2%7C
*June 21, 2016*

**maths**

ok now you do the same.
*June 20, 2016*

**Math**

Let z = x+yi Then we have x^2+y^2-2x+2yi+xi-y=2i That means we have x^2+y^2-2x-y = 0 2y+x-2 = 0 Thus, x = 2-2y and so 4-8y+4y^2+y^2-4+4y-y = 0 5y^2-5y = 0 5y(y-1) = 0 so, y=0 x=2 or y=1 x=0 Or, z=2 or z=i I'll let you verify that both of those z values satisfy the original...
*June 20, 2016*

**CALCULUS**

surely the initial mass is positive. Kind of makes things more real. Looking at the original equation, if y(0) < 0, we have exponential growth, not decay.
*June 20, 2016*

**CALCULUS**

this is just like the other one. You already know about radioactive decay, and how it is an exponential function, right?
*June 20, 2016*

**CALC PLEASE HELP**

dy/dt = ky dy/y = k dt ln y = kt + ln c y = c*e^(kt) Now plug in your values to determine c and k.
*June 20, 2016*

**maths**

triangles BDA and BDC are congruent.
*June 20, 2016*

**Calculus**

you can find the area B of the base (a triangle), and its height (the z-intercept) v = 1/3 Bh
*June 20, 2016*

**Math (pre-celc 12)**

the order does not matter. There are 21P3 ways to select an ordered group of 3 items from 21. Whoever is chosen first, there are 21 available people. 20 for the 2nd, and 19 for the 3rd.
*June 20, 2016*

**Math**

So far you have only mentioned 4 places. Any data on the other three? A lot of possibilities will fit what you have required so far.
*June 20, 2016*

**physics**

10+12 √(10^2+12^2)
*June 20, 2016*

**algebra**

2x+2x+2+2
*June 20, 2016*

**Science chemistry**

I only found TETRACHLOROMETHANE
*June 20, 2016*

**Maths**

(n+1)/d = 1/3 n/(d+1) = 1/4 If that's too hard to work through, then just consider that 5/15 = 1/3 4/16 = 1/4
*June 20, 2016*

**Mathematics**

14000(1+.12)^2 vs 14000(1+.12/2)^(2*2)
*June 19, 2016*

**math**

2(r^4-1)/(r-1) = 30 r=2 The last 4 terms don't matter, unless you are interested in how many there are.
*June 19, 2016*

**Math**

t+b+f = 7.56 f = 2t 1.1t + 1.25b + f = 8.68 Now just crank out the desired answers
*June 19, 2016*

**Maths**

w/250 = cot50°
*June 19, 2016*

**Physics**

How can you explain work, in regards to electricity? I understand it as the product of energy used, usually displacement. I cant understand or explain it as far as electricity is concerned. I'm not sure if I understand it at all.
*June 19, 2016*

**Math**

oops. 2sin^2(1/2 y) = 1 - cosy
*June 19, 2016*

**Math**

f(x+y)-f(x) = sinx cosy + cosx siny - sinx sin^2(1/2 y) = 1 - cosy That should get you on your way... The rest is just algebra.
*June 19, 2016*

**trigonometry**

draw a diagram review the tan function see that tanθ = 36/20
*June 19, 2016*

**Maths**

It never hurts to review. I help students with advanced algebra and calculus, and am constantly amazed and frustrated at how much of their elementary arithmetic they have forgotten. Look over your topics, try out some problems, and make sure that when you see them you don'...
*June 19, 2016*

**math**

if sinθ = 1/3, 2cot^2θ + 2 = 2csc^2θ = 2(3)^2 = 18 = (9)+(224) = 233
*June 19, 2016*

**math**

just subtract (5x^3-13)-(2x^3-4x+9) = 3x^2+4x-22
*June 19, 2016*

**mathematics**

.0x0 .3x1 .6x2 .9x3 .000 .341 .682 Can't pin it down any better than that
*June 19, 2016*

**Math 5**

If there were 15 correct answers, then there were 5 wrong, so 15*5 + 5*2 = ?
*June 18, 2016*

**math**

Tn = 2n
*June 18, 2016*

**Math**

1.4/7
*June 18, 2016*

**Math**

The speeds are x and x+8 since distance = speed * time 60(x + x+8) = 4320
*June 18, 2016*

**math**

a = 5-2√6 a^2 = 49-20√6 1/a^2 = 49+20√6 Now just add up a^2 + 1/a^2
*June 18, 2016*

**Mathematics**

surely you can do some of those. Which ones present a problem? area of sector: 1/2 r^2 θ arc length: rθ
*June 18, 2016*

**Mathematics construction**

ok now what? Surely you can bisect a 90-degree angle...
*June 18, 2016*

**math @Reiny**

oh, yeah. Good call.
*June 18, 2016*

**math**

well, geez, just plug in the values. You have (x-1)(x+3) = x^2 + 2x - 3 = x^2 + (a+1)x + b Now it should be clear what a and b are if the two polynomials are identical.
*June 18, 2016*

**math**

If I read you right, we have v^2 + 4√3 v - 15 = 0 (v-√3)(v+5√3) = 0 Not sure what you mean by "its coefficient".
*June 18, 2016*

**Science**

it is at its highest when the velocity drops to zero and it starts to fall. v = Vo - at = 98 - 9.8t ...
*June 18, 2016*

**math**

see earlier post
*June 18, 2016*

**physics**

F = ma now just plug in your values.
*June 18, 2016*

**area of a circle**

clearly the radius is 3, since that's how far away the point is from the x-axis, right? Now crank it out.
*June 18, 2016*

**Algebra**

well, they have said that a=3 r=5 The 23rd term is thus 3*5^22 That is, you start with 3 and multiply by 5 22 more times to get to the 23rd term. Next, we have a + 7*4 = 13 so, a = -15 T23 = -15 + 22*4 Any two consecutive terms of a geometric sequence have a common ratio. In ...
*June 17, 2016*

**math**

The multipliers are 1,3,9,27, ... As powers of 3, those are 0,1,2,3,... You can't say 7*3^x because the first term (x=1) has not been multiplied yet.
*June 17, 2016*

**math**

I can see only (5,-5) and (-5,5) any other pairs of additive inverses do not differ by 10
*June 17, 2016*

**Math**

terms of what?
*June 16, 2016*

**math**

since mass is proportional to volume, the ratio would be (15/25)^3
*June 16, 2016*

**Maths**

well, 3/7 + 5/8 * 4/7 = 11/14
*June 16, 2016*

**maths**

2(24+84)/3 * 100
*June 16, 2016*

**math**

4/3 pi r^3 = 1200 cm^3 r^3 = 900pi cm^3 ...
*June 16, 2016*

**Math**

pi r^2 = 9.5 c = 2pi r = 2pi √(9.5/pi) = 10.93 m
*June 15, 2016*

**Calculus**

how about some parentheses, so we know what's where? Also, it would be polite to indicate just what it is you want to know. For starters, just enter your expression in the box at wolframalpha.com and it will show you the graph, its derivative and integral, and more. Be ...
*June 15, 2016*

**math**

at 1 pm Train 1 had gone 300 miles. Now you know that one train is going 5/4 as fast as the other. see what you can do from here.
*June 15, 2016*

**physics**

font is garbled. Try explaining. review dot and cross products
*June 15, 2016*

**math**

2 hrs at 50km/hr = 100 km So, how long does it take to go that far at 40 km/hr?
*June 15, 2016*

**math**

a 180° rotation (in either direction) just changes the signs of all the coordinates.
*June 15, 2016*

**Algebra**

surely you are not saying that those two answers are equivalent. (2±√10)/2 is the correct solution. If you try plugging in 2√10 you will see that it does not do the job.
*June 15, 2016*

**Math**

NYC = 10 ~NYC = 90 NYC & 18 = 10 ~NYC & 18 = .70*90 = 63 Knowing that there are 73 18-yr-olds, and that 10 of them are from NYC, ...
*June 15, 2016*

**Math**

if the speed of the prop is x, then the jet is 4x. Since distance = speed * time, we have 4x*2 + x * 1/2 = 850
*June 15, 2016*