Thursday
August 25, 2016

Posts by steve

Total # Posts: 42,770

Math(Please Help Assignment Due Tomorrow)
you can get a handle on this stuff at http://davidmlane.com/hyperstat/z_table.html
June 23, 2016

Math (pre-celc 12)
or, now that you know f, f+g-f = g so, g(x) = (10-3x)-(x-2) = 12-4x
June 23, 2016

Math (pre-celc 12)
come on; this is Algebra I (f+g)-(f-g) = 2g 2g = (10-3x)-(5x-14) = -8x+24 g(x) = -4x+12
June 23, 2016

Math (pre-celc 12)
(f+g)+(f-g) = 2f so, 2f(x) = (10-3x)+(5x-14) = 2x-4 f(x) = x-2 You can find g(x) in a similar way.
June 23, 2016

for all real numbers x and y,it x*y=x(x-y) then x*
Let z = x*y = x(x-y) x*(x*y) = x*z = x(x-z) = x(x-(x(x-y)))
June 23, 2016

Math
If the height is h miles, then h cot3.5° - h cot9° = 13
June 23, 2016

math
extra parentheses are often useful when entering expressions online, as formatting is often rudimentary The text formatting in printed material often makes the parentheses unnecessary In any case, if the expression is unambiguous without the parentheses, they are unnecessary.
June 23, 2016

Math
There is no such number. Now, if you mean integers, then that would be 6499 or 6500 depending on your rules for rounding with terminal 5's. And next time ask a question, instead of just dropping a misspelled sentence fragment with bad grammar.
June 23, 2016

Chemistry
so, you have 75 grams How many moles of bentoite is that? Note that each mole of bentoite contains 3 moles of Si.
June 23, 2016

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

Math
14
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

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