Sunday
September 21, 2014

Posts by steve


Total # Posts: 25,115

math
You can figure out the mass of silver, then do all the conversions of mass to volume and back, or you can note that density(Al)/density(Ag) = 2.57 So, volume(Al)/volume(Ag) = 2.57 But, the volume of a sphere scales as the cube of the radius, so the radius scales as the cube ...
September 7, 2014

math
(12-2)p^7 = 10p^7
September 7, 2014

algebra
do it just the way to multiply 2-digit numbers: (23)(45) = (20+3)(40+5) = 20*40+3*40+10*5+3*5 = 1035 (7-6y)(7-4y) = 7*7 + 7(-4y) - 6y(7) - 6y(-4y) = 49 - 28y - 42y + 24y^2 = 49 - 70y + 24y^2
September 7, 2014

algebra 2
all polynomials have domain of all real numbers. All polynomials of odd degree have range of all real numbers, y=0 when x = ∛4 x=0 when y = -4
September 7, 2014

Calculus
You know the roots are x = (m±√(m^2-4))/2 So, if m<=2 there are not two real roots, so the total area is the same as the integral. If m>2, then you need to divide the integral into 3 parts, with the roots as the limits of integration. Reiny's solution of...
September 7, 2014

Algebra
You have two points on the line: (2,5) and (6,9). So, the line has slope=1, and its equation is c = m-3
September 7, 2014

Geography
∂2u/∂x∂y
September 7, 2014

physics
8.2m / 3.7m/s = 2.2 s
September 7, 2014

physics
just solve for a in 4100t - 17/2 t^2 = 9400t - a/2 t^2 a/2 t^2 = 5300t + 17/2 t^2 at^2 = 10600t + 17t^2 a = 10600/t + 17
September 7, 2014

Quick question
Just how would you propose we do asl in a text forum?
September 7, 2014

Calculus
clearly, each rectangle with upper-right corner at (x,y) has area a = xy Since y = 9-x^2, the area is just a = x(9-x^2) Not sure what you need to do with that information. The question is a bit vague.
September 7, 2014

Math - Urgent
(a) each term is -1/3 the previous term (b) each term is -4 times the previous term Just take the first two terms and find their ratio. Then check to make sure the same ratio is there for the next two terms, and so on.
September 7, 2014

math
the slope of the given line is -1/2 so, the slope of perpendiculars is +2 So, the line you want is y+12 = 2(x+7)
September 7, 2014

Precalc
try C(x) = 4.00 + 0.40⌈10x⌉ where ⌈z⌉ is the ceiling function (the least integer greater than z) For example, ⌈2.37⌉ = 3
September 7, 2014

science/math (mean)
I get 44.60333333... So, to three decimal places, that would be 44.603 However, since all the values are given to two places, I would have given the same answer you did.
September 7, 2014

math
6*22 + .18 * 2766.50 = 629.97
September 7, 2014

math 8
when multiplying powers, add the exponents. when raising a power to a power, multiply exponents. This is because, for example, (x^2)^3 = (x^2)(x^2)(x^2) = x^(2+2+2) So, you have #5: 8^3 * 8^7 = 8^(3+7) = 8^10 #11: (5/8)^3 = 5^3/8^3 = 125/512 #12: ((-2/9)^3)^5 = (-2/9)^15 = -2^...
September 7, 2014

C programming
Hmm. Looks good to me. Can you produce the results for a few values of x? Do you at least get cosh(0) = 1.0 ?
September 7, 2014

math 12
If C=D, C-D=0 and you cannot divide by zero.
September 7, 2014

Math
graphing what?
September 7, 2014

physics
658.1m / .03m/yr = 21936.7 yr
September 7, 2014

physics
in MKS units, .440kg * 98 mi/hr * 1000m/0.62mi * 1hr/3600s = .440*98*1000 / .62*3600 m/s = 19.32 kg-m/s
September 7, 2014

Algebra
correct. So, plug in either point. Using (-2,-3), you have -3 = (-2/7)(-2) + b b = -25/7 so, y = -2/7 x - 25/7
September 7, 2014

Physics
x(3) = 90m x(2) = 40m total distance: 50m total time: 1s avg speed: 50 m/s
September 7, 2014

Math
going down: 5/2 seconds going up: 5/1 seconds so, down+up = ?
September 7, 2014

Geometry help
Did you draw a diagram? AC = CD AD = AC+CD #1 ok #2. The calculation for x is just as in #1. AD = AC+CD = 7+7 = 14 #3. AD=AC+CD = 2(AC), so 6x-4 = 2(4x-3) x = 1 CD = 1 #4. As in #3, 12-x = 2(3x-1) x = 2 CD = 5
September 7, 2014

AP Alegebra
(√x+1)/(√x-1) multiply top and bottom by √x+1 and you have (√x+1)(√x+1) / (√x-1)(√x+1) (x+2√x+1) / (x-1)
September 7, 2014

Law of Sines
you have C and c and a, so you can find A using sinA/a = sinC/c Now, having A and C, you know that A+B+C=180, so you can easily find B. Then, use the law of sines again to get b: b/sinB = c/sinC = a/sinA
September 6, 2014

Algebra
reflecting through where? x-axis? y-axis? origin? Just to remind you, reflecting through x-axis: (x,y) -> (x,-y) y-axis: (x,y) -> (-x,y) (0,0): (x,y) -> (-x,-y)
September 6, 2014

AP CAlc. AB
since |sinx| <= 1, x^2 sin(1/x) -> 0 as x->0 So, all that's left is 3k. Doesn't really matter whether k is positive or not.
September 6, 2014

Physics II
What is the sign and magnitude of a point charge that produces a potential of -2.00 V at a distance of 3.00 mm?
September 6, 2014

Calculus
As a sequence, let Tn be the time taken to meet the car for the nth time. T1 = d/(b(c+1)) T2 = T1*b/(b(c+1)) ... Tn = d/(b(c+1))^n The sum of this series, with a = d/(b(c+1)) r = 1/((c+1)) is S = a/(1-r) = d/(b(c+1)) / (1 - 1/((c+1)) = d/bc That is the total flying time. So, ...
September 6, 2014

AP Physics
since time = distance/speed, 16.5/s + 16.5/340 = 2.90 s = 5.787 m/s
September 5, 2014

AP Physics
since the car is going 17 km/hr faster, and it is 0.130 km behind the truck, it will take 0.130/17 = 0.0076 hours You may want to express that in seconds :-)
September 5, 2014

math
that would be 21*16 + 18*20 = 696g
September 5, 2014

math
P = a-c = (a+b)-(b+c) = 49-13 = 36
September 5, 2014

algebra
y increases by 4 when x increases by 1. So, look for something like y = 4x+b Now, when x=1, y=0, so we end up with y = 4x-4
September 5, 2014

algebra
the height is the y-value at the vertex, where x = .658/.000814 Since y = x(.658-.000407x) the roots are at 0 and 1616.7 The bridge spans that distance
September 5, 2014

algebra
first rearrange the terms so you have 2x^2 + 2x - 5 = 0 Now just plug in the formula, where a = 2 b = 2 c = -5 x = (-2±√(2^2 + 4*2*5))/(2*2) = (-2±√44)/4 = (-1±√11)/2
September 5, 2014

math
using the same ratio, x/125 = 400/20000 x = 2.5
September 5, 2014

Physics
(a) 31.1t = 1/2*4.11t^2 t = 15.134 seconds Now use that t for parts (b) and (c)
September 5, 2014

Physics
see related questions below, and change the numbers as necessary. The key is to separate the 2.2 seconds into the falling time and the return time.
September 5, 2014

math
review scientific notation. There is a number and a power of 10. the number must be between 1 and 10. (Less than 10) When adding, the powers of 10 must be the same, just as you need a common denominator to add fractions. Then you can just add the numbers as usual, keeping the ...
September 5, 2014

Math
the chance it will not snow on a day is 3/5, so for two days, that is 3/5 * 3/5 = 9/25
September 5, 2014

Math
the ratio of 3.25in : 4cm for the short side is 3.25*2.54/4 = 2.07 close enough for jazz. Now use that scale factor to enlarge 4.6cm. Probably should express the answer in inches, as well, since that was the original frame size unit. Actually, you don't need the scale ...
September 5, 2014

math
just drag out your formula for the area of a circle: A = πr^2 In this case, r = 7 yd, so A = π(7 yd)^2 = 49π yd^2
September 5, 2014

Operating Systems
pages are accessed in the order acbd*a*c*b*d*e*f* Bad luck, that.
September 4, 2014

math
each photo is 2x2, so 2*60 = 120
September 4, 2014

Math
you can solve for x or for y. Which is of interest to you?
September 4, 2014

math word problem
300(1+.04)^5
September 4, 2014

Pre-Calc
As usual, draw a diagram. It is clear that if the height of the mountain is h, and the tower is at a distance x from the mountain, (h-180)/x = tan 21°35' h/x = tan 24°48' Eliminate x and you have (h-180)/tan21°35' = h/tan24°48' Now just solve for h
September 4, 2014

Geometry
I'd say 56 and 75 Maybe a bit more context would be helpful...
September 4, 2014

AP Physics
total distance: 7.7*4.5*60 + 2.8*2.8*60 = 2549.4 m total time: (4.5+2.8)*60 = 438 s so, avg velocity is 2549.4/438 = 5.8 m/s
September 4, 2014

math help!!
you have the difference of two squares: (a/6)^2 - (b/7)^2 So now the factoring is easy, right?
September 4, 2014

math
For the 4th test, 79+97+85+x = 4*85 so, x = 79 Then, for the 5th test, 4*85 + y = 5*(85+3) so, y=100
September 4, 2014

math
r = 6w+1 r+w = 50 so, r = 43
September 4, 2014

math
-10 -3 5 16 vs -3 5 -10 16 The second list would be unchanged if the new numbers were used.
September 4, 2014

Math
no way to solve for anything without an = sign
September 4, 2014

Alhebra1
3^2+(5+2)•4- 6/3 First, parentheses: 3^2+7•4-6/3 Next, powers: 9+7•4-6/3 Next, multiplication and division: 9+28-2 Finally, addition and subtraction: 35 As that is not one of the choices, I suspect a typo. Find it, fix it, and then follow the same steps.
September 4, 2014

Math
s = 2j+5 i = 4j s+j+i = 96 Now solve, using your method of choice.
September 4, 2014

algebra
8+3x(6-4)-1=13
September 4, 2014

physics
the height y of the ball at distance x is y = x tanθ - g/2v^2 sec^2 θ x^2 so, we want to solve for v in 110 - 9.8/v^2 * 110^2 = 0 v = 32.83 m/s
September 4, 2014

math
since the amount drops by 1/2 every T, the function is f(t) = (1/2)^(t/T) But, 1/2 = e^-ln2, so f(t) = (e^(-ln2))^(t/T)) = e^(-ln2/T t) = e^(kt)
September 4, 2014

math rounding
before we can do much, you have to fix "The value of the thousands digit is double that of the the thousands digit."
September 4, 2014

Math
review what supplementary angles are, then solve 10x-25 + 15x+50 = 180 Now that you have x, evaluate the two angles.
September 4, 2014

math
If there were already n tests, then if Diane scored d and Peter scored p, then with the current average of a, n*a + 97 = (n+1)(90) n*a + 73 = (n+1)(87) so, we can eliminate the a and have (n+1)(90)-97 = (n+1)(87)-73 (n+1)(3) = 24 n+1 = 8 n = 7
September 4, 2014

algebra
there is no solution. If you subtract 3x from both sides, you have 0 = -3 Is there a typo?
September 4, 2014

Geometry
GB has length √25 GF has length √85 I expect you can compare those Do others in like wise.
September 4, 2014

Algebra1
[(40+5)-3^2]÷9•2 [45-9]÷9•2 36÷9•2 4•2 8
September 4, 2014

Math
y = x^2+16x+64 = (x+8)^2 + 0 so, the vertex is at (-8,0)
September 4, 2014

Math
y = x^2+16x+64 = (x+8)^2 + 0 so, the vertex is at (-8,0)
September 4, 2014

math
ages now: t and g 16 years ago, (g-16) = 8(t-16) 8 years from now, (g+8) = 3(t+8) Hmmm. solving those two equation, I don't get integer solutions. That's ok, but unusual. If I have gotten something wrong, fix it and follow through, finishing with the ratio (t-8)/(g-8) ...
September 4, 2014

Math
looks good to me.
September 4, 2014

Math
Review conditionals: if hypothesis then conclusion 1. D 2. D
September 4, 2014

algebra
the point-slope form tells you that y-3 = 2(x-1) Rearrange things to get y = 2x + 1
September 4, 2014

(Please Help!) Analytic Geometry
google it - wikipedia has a good discussion
September 4, 2014

Ms Sue Please Help ! Analytic Geometry
what do you mean "identify the points"? 9x^2 + 4y^2 -54x-16y + 61 =0 9x^2-54x + 4y^2-16y = -61 9(x^2-6x) + 4(y^2-4y) = -61 9(x^2-6x+9) + 4(y^2-4y+4) = -61 + 9*9 + 4*4 9(x-3)^2 + 4(y-2)^2 = 36 (x-3)^2/4 + (y-2)^2/9 = 1 ellipse with major axis vertical, semi-axes of ...
September 4, 2014

science
you know that the height at time t seconds is h(t) = 24 + 24.5t - 4.9t^2 so, just solve for t when the stone hits the ground (its height is zero).
September 4, 2014

Physics
Hmmm. bobpursley is usually right on these matters. I'll have to think on it a bit to see why the initial height makes no difference.
September 4, 2014

Physics
the time for the pellets to hit the ground is A: h + 36.3t - 4.9t^2 B: h - 36.3t - 4.9t^2 I expect you will need to know h (the height of the cliff) to solve for the two values of t and take their difference. A: t = (-36.3 ±√(1317.69+19.6h))/9.8 B: t = (36.3 &...
September 4, 2014

Math (data)
good riddance to the bums.
September 4, 2014

algebra
the arrow points to the smaller number 6 < x means six is less than x x > 2 means x is greater than 2 <= means less than or equal >= means greater than or equal So, you want -6 < x < 6 think of the point of the arrow as small, so it's next to the smaller ...
September 4, 2014

MATH
one way is to convert all to decimals and compare. the other way is to recall that for a given numerator, the larger the denominator, the smaller the value. That is 1/10 is less than 1/7, and so on Now, you have several numbers which are all greater than 2 by some amount Those...
September 4, 2014

Math
if there are x yellow cars, there are 9x white cars so, add them up: x + 9x = 40 10x = 40 x = 4 Now you know how many yellow cars there are, so you can figure out how many white ones there are.
September 4, 2014

math
the domain of y is all real numbers except odd multiples of 1/2. So, your logic is sound, but the domain is all reals except 1/2 + k for k in Z.
September 4, 2014

Mathematics for business & finance
sounds like a good deal. was there a question somewhere in there?
September 4, 2014

thank u
we aim to please...
September 4, 2014

Algebra 2
since the vertex occurs at x = -b/2a, y = a(-b/2a)^2 + b(-b/2a) + c = b^2/4a - b^2/2a + b = -b^2/4a + c
September 4, 2014

7th grade math
you want 3+x > 0 so, subtract 3 from both sides to get x > -3 so, pick any value greater than -3
September 3, 2014

geometry
6x+17 Maybe you could provide a bit more context here ...
September 3, 2014

Math
It is in fact C D is just a quadratic in (2/x-4), because if you substitute u=2/x-4, you have just 3u^2+5u-2=0 It is C because as you say, there is not a term with twice the exponent of the other.
September 3, 2014

math
25q + 5(2q) + 1(3q) = 760 38q = 760 q = 20 so, 20 quarters, 40 nickels, 60 pennies
September 3, 2014

MATH1112
In the first case, we have (1+p)(1-q) In the second case, we have (1-q)(1+p) Looks the same to me, and for the stated reason.
September 3, 2014

Math
since the height:shadow ratio is the same for both, h/21 = 68/96
September 3, 2014

Math 112
Bogus. 1% = 0.01 because "percent" means "per 100" 1 per 100 = 1/100 = 1% .01% means .01/100 = .0001
September 3, 2014

Honors Pre Calculus
Not sure what the little  characters mean, but unless (1-sinx)^2 = |cosx| it can't be true.
September 3, 2014

alegbra
the degree is the sum of all the powers of variables. If no power is given, then assume it is 1. SO, the terms have degrees 3,2+1,2,1+2 The degree of the polynomial is the highest degree among the terms. I see no like terms to combine
September 3, 2014

math
Ratios are written 3:4, not 3.4 Initially, r/y = 3/4 Later, (r-3)/(y-6) = 4/5 Solve those two equations to get r=27, y=36
September 3, 2014

AP Physics
total distance: 8.5-3.6 = +4.9 cm total time: 4.5 - (-1.5) = 6.0s avg velocity: +4.9/6.0 cm/s
September 3, 2014

math help!!
you have the difference of two squares (3n)^2 - 5^2 That should help.
September 3, 2014

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