Tuesday
February 9, 2016

Posts by Steve

Total # Posts: 37,527

statistics help please
͡° ͜ʖ ͡°
December 12, 2015

Algebra
all polynomials are defined for every real number. So, the domain is all reals. Since a sloping line extends forever in both directions, what's your best guess as to the range? Surely you can fill in the table. Just multiply x by 6, right?
December 12, 2015

Algebra
x-intercept is where y=0 y-intercept is where x=0 so, just plug in 0 for y or x and find the two intercepts. Then just connect them with a line. Done.
December 12, 2015

calculus
just divide each term by x^2 and use the normal power rule: ∫x^n dx = 1/(n+1) x^(n+1)
December 11, 2015

math
This can be easily confirmed by noting that the equation is an ellipse: (x-1)^2/16 + (y+2)^2/4 = 1 The major axis is on the line y = -2, so that's where the tangents are vertical.
December 11, 2015

Ap physics 1
If we set the center of mass at 0, then we have 3.12*10^5 * 2.46*10^8 = m*d where m is earth's mass and d is the distance to the center of the planet.
December 11, 2015

Physics grade 11-
72 km/hr = 20 m/s So, the deceleration is (20m/s)/(.1s) = 200m/s^2 Now the force F=ma, so ...
December 11, 2015

Calulus
The FTC says that the value is F(6)-F(1) where dF/dx = 4e^x-3 F(x) = 4e^x - 3x + c F(6) = 4e^6 - 18 + c F(1) = 4e^1 - 3 + c So, ∫[1,6]4e^x-3 dx = 4e^6-4e-15
December 11, 2015

Calulus
y = 2x^3-3x^2+9x+5 y' = 6x^2-6x+9 y" = 12x-6 Now, just apply the basic rules extrema at y'=0 and y"≠0 y increasing where y' > 0 y concave up where y" > 0 inflection points at y"=0 Note: There may not be any extrema, and so on. ...
December 11, 2015

Algebra 1
try using the two-point form of the line. Your two points are (2,-17) and (8,-47)
December 11, 2015

Algebra 1
pick the one best suited to the problem. You know that you have a rate 0\of .50 for every mile. So, if x is the number of miles, you know you will have something like y = .5x But you have a flat fee of 4.25, regardless of the miles, which is tacked on as soon as the meter ...
December 11, 2015

Calulus
base side x height y 2x^2+4xy = 300 ==> y = (300-2x^2)/(4x) v = x^2y = x^2(300-2x^2)/(4x) = 75x - x^3/2 dv/dx = 75 - 3x^2 dv/dx=0 at x=5 So, the shed is 5x5x12.5, with v=312.5 ft^3
December 11, 2015

Math
since distance = speed * time, if the current is c and her speed is s, 35(s-c) = 1.75 15(s+c) = 1.75 Now just solve for c.
December 11, 2015

Calculus
cube side = x, so the area a = 6x^2 da/dt = 12s dx/dt Now just plug in your numbers.
December 11, 2015

Pre Algebra
Judging by the choices, I guess the burn time is in hours. So, you want the height h = 3*24/15
December 11, 2015

Pre Algebra
I suspect a typo: 80 should be 90. If so, then clearly, the burn time is just 15 times the height. You don't say whether the time is in hours or minutes. I suspect minutes, but that will require quite a tall candle, if you figure out how many minutes there are in 3 days.
December 11, 2015

Math
nope. Just the definition of the sine: h/14 = sin 70° For the law of cosines, you need two sides and their included angle.
December 11, 2015

Math
original b = h+3 (1/2)(b+3)(h+3) = (1/2)(h+6)(h+3) = 14 Now just solve for h, and then get b.
December 11, 2015

hbi pact for adults
well 50 lbs is 50 times a much as 1 lb, so expect 50 times as many nails.
December 11, 2015

math
that would be 3000/200000 = 3/200 express that as a percent.
December 11, 2015

Math
Let's scale down the figure by a factor of 25, so it is similar to a triangle with sides 4,10,11 you can use Heron's formula. sqrt(12.5(12.5-4)(12.5-10)(12.5-11)) ≈ 20 or, you can note that 4^2 = 10^2+11^2-2*10*11*cos(x) cos(x) = (100+121-16)/220 = 41/44 the area...
December 11, 2015

Chakote school solapur
just use the formula: 1/R = 1/10 + 1/20 + 1/60 The voltage does not matter. The formula works because each resistor allows a current to pass, and the currents add up to the total. Since E=IR, I=E/R, and you have a total current of 12/10 + 12/20 + 12/60 That current is the ...
December 11, 2015

maths (trigonometry)
Notice how Damon cleverly descried a poorly constructed problem, and took a shortcut!
December 11, 2015

Math
Must be some special form. I tried an online integrator, and got (1/2)^(y+1) Γ(y+1)/y! But since Γ(y+1) = y!, that gives your answer. I'd suggest looking into integral forms involving the gamma function.
December 10, 2015

Algebra
you have the formula. Just plug in t=6 To find how long it takes to get to a million, 2105.22e^0.03t = 1000000 e^.03t = 475 .03t = ln 475 = 6.1633 t = 205.44 years Looks like 3% isn't gonna cut it, especially if you include inflation.
December 10, 2015

Math factoring
15x^2-35x+10 5(3x^2-7x+2) 5(3x-1)(x-2)
December 10, 2015

Math question word
x = desktop cost y = laptop cost x = y+350 .07x + .095y = 305 Now just solve for x and y
December 10, 2015

Finite Math
C(30,3) = 4060 any number means some subset of the power set of 30 elements. That is 2^30 = 1,073,741,824
December 10, 2015

Math
oh, ok total fruits: 12+4+8=24 so, now what do you think?
December 10, 2015

Math
'Twas brillig, and the slithey toves ...
December 10, 2015

compare and order fraction
or, if you use a common denominator -- in this case, 60. For example, 4/6 = 40/60 ...
December 10, 2015

MATH
Aside from the copy/paste of the inequality symbols, ok. Special symbols in various fonts get garbled at times. 22 <= 6x-2 <= 4x+16 24 <= 6x <= 4x+18 Now things start to get messy. You can't just subtract 4x from part of the setup; all or nothing. So, I'd ...
December 10, 2015

math
since 3/4 = 30/40, what do you think?
December 10, 2015

MATH
you can do both at once 3 < 5x-27 < 53 30 < 5x < 80 6 < x < 16
December 10, 2015

@Damon - Nice Catch
duh -- read twice, write once.
December 10, 2015

Algebra 2
Oops. That is just the integer lengths. I'm sure you can set down the two inequalities restricting x and y.
December 10, 2015

Algebra 2
7 <= x+y <= 22 So, just start listing x y 1 6..21 2 5..20 . . . 6 1..16
December 10, 2015

math
L=56+3D
December 10, 2015

math
3 months is 1/4 year, so discount by 2%
December 10, 2015

Maths
n(AuBuC)=12 n(AuB)=8, so n(C)=4 n(A'uB'nC)=n((AuB)'nC) That help?
December 10, 2015

Math
well, just plug and chug. f(x+h)-f(x) = 1/(x+h-1) - 1/(x-1) = ((x-1)-(x+h-1))/((x-1)(x+h-1)) = (x-1-x-h+1)/((x-1)(x+h-1)) = -h/((x-1)(x+h-1)) Now, divide that by h, and you have -1/((x-1)(x+h-1)) Now you can take the limit as h->0, and you end up with -1/(x-1)^2 at x=2, ...
December 10, 2015

Pre-calculus
This is just Algebra I. If there are a grams of A b grams of B .14a + .29b = 34.53 130a + 90b = 25430 Now just find a and b.
December 10, 2015

Algebra
they are the same, since multiplication is commutative.
December 10, 2015

maths
1/15th failed, so 14/15 passed
December 10, 2015

Algebra discount price
p-75 is ok But, a 55% discount means you only pay 45%, or p*.45 For C, just set them equal, as asked: p-75 = .45p .55p = 75 p = $136.36
December 10, 2015

algebra
OK. Y=28-6x. But, y>x, since it is the middle So, we have 28-6x > x 28 > 7x x < 4 So, we have several choices 3,10,18 2,16,13 1,22,8 ... But y is the middle, so only 3,10,18 works.
December 9, 2015

geometry
Note that the triangle described is a right triangle. The orthocenter is at the right angle, since the triangle can be inscribed in a circle, with the hypotenuse as the diameter.
December 9, 2015

similarfigures
it's called a proportion
December 9, 2015

analtyic geometry
so, add up the sides to make 260. That will give you x, and thus the dimensions of the yard.
December 9, 2015

Math cosine law
Did you draw your triangle? Did you review the law of cosines? x^2 = 185^2 + 325^2 - 2*185*325*cos18°
December 9, 2015

Math
the Greek letter is pi, NOT pie!! just use your addition formulas. sin(x-y) = sinx*cosy - cosx*siny Draw your triangles for x and y. sinx = √3/2 means cosx = 1/2 cosy = 12/13 means siny = 5/13 Now just plug in the numbers.
December 9, 2015

Calculus
all polynomials are continuous over their entire domain
December 9, 2015

Maths
well, you can see from the 2nd equation that 3y=7x-3. So, 6y=14x-6 Plug that into the 1st equation to find x, and then you can get y. Or, equivalently, multiply the 2nd by two and then you have 4x+6y = 21 14x-6y = 6 Now just add the two equations and y vanishes, leaving 18x=27...
December 9, 2015

Math
all polynomials are continuous over their entire domain
December 9, 2015

Maths
2x^2+8x-10 2(x^2+4x-5) 2(x+5)(x-1)
December 9, 2015

Pre- Algebra
the smallest set is the natural numbers: 1,2,3,... Next is whole numbers: 0,1,2,3,4... Next is integers: ...-2,-1,0,1,2,... Next is rational: these are all the fractions 1/2, 3/7, and so on Next is irrational: everything else Real numbers include all of the above Finally there...
December 9, 2015

probability
your first answer is the probability of drawing RRB in that order. But, if all you want is two reds and a blue, you need to multiply that by 3!/1!2!=3 because there are that many indistinguishable ways to reorder the balls. In other words, you have RRB, RBR, BRR They are all ...
December 9, 2015

Math
The angle does not really matter. Using similar triangles, h/20 = 30/52
December 9, 2015

math
9x10^8 / 3x10^7 = 9/3 x 10^1 = 30
December 9, 2015

math
#1 (a) and (b) Now, what are your thoughts on the others? I see no diagrams for 2,3,4
December 9, 2015

Math
What is the slope of your given line? Parallel lines all have the same slope.
December 9, 2015

Math
1/12 * 1/12 Given a drawn number, there is a 1/12 chance that it will be drawn next time.
December 9, 2015

calculus
or, you can integrate over dy, and avoid the split: In this case, the two lower bounding curves are x = y^2/4 x = 3-y ∫[2,4] y^2/4 -(3-y) dy = 14/3 Checking with Damon's method gives ∫[-1,1] 4-(3-x) dx + ∫[1,4] 4-2√x dx = 2 + 8/3 = 14/3 So, each ...
December 9, 2015

algebra
y = (6/3)x
December 9, 2015

Geometry
Complete the 2 column proof. Given m<rst = 5x and m<uvw = 7x <rstand <uvw are supplementary. Prove x=15 m<rst=5x and m<uvw=7x <rst and <uvw are supplementary given m<rst + <uvw = 180 definition of supplementary angles 5x+7x = 180 ? 12x=180 ? x=15 ?
December 9, 2015

Math
expand parentheses to get 36w+24+17+9w collect like terms to get 45w+41
December 8, 2015

Algebra
25*35 - (25-4)(35-4) =
December 8, 2015

Physics
clearly the angle is x (from directly ahead), where sin(x) = 25/31 If it takes t hours, then 0.3^2 + (25t)^2 = (31t)^2
December 8, 2015

alegbra 2
(7y+6)/(20x^2+20) = (21y+18)/(60x^2+60) just multiply top and bottom by 3
December 8, 2015

Math
what is 1/2 divided by 3?
December 8, 2015

math
c = 40.00 + .05m
December 8, 2015

Geometry
correct, if somewhat murky.
December 8, 2015

Grover Cleveland high school
study the equation of motion. If he indeed fell, starting at 10 m/s downward, then his height after t seconds was h(t) = 400 - 10t - 5t^2 But I doubt he pushed off with such a downward speed. Maybe you can modify h(t) to reflect the actual scenario.
December 8, 2015

precalc
I'll do a freebie for you. Maybe you can attempt the rest and show your work. The major semi-axis half the distance between the major vertices. Similarly for minor. #1: maj semi = 3 min semi = 2 x^2/4 + y^2/9 = 1 #3 is similar, but the center has been translated. Recall ...
December 8, 2015

Math
#1. Each nested side is 1/√2 as long as the previous side. Use that to find the length of the nth nested side. #2. Since the last digit is 8, there are 80 of them: 18,28,...808 Now you know the sum of the numbers from 1 to 80 is 80*81/2. So, you have 10 times that sum, ...
December 8, 2015

Math
I'll get you started with A. Its cost for n years is A(n) = 12500 + 300n + 3(36000/25)n do the same with B, changing the numbers as needed. Then you can make the table and compare costs for 2 years.
December 8, 2015

Math
right on.
December 8, 2015

Math
correct.
December 8, 2015

Mulitvariable Calculus
any text on vector analysis or differential geometry will discuss this topic. And google is your friend.
December 8, 2015

math
√x+y=11 x+√y=7 can't you think of some nice simple numbers that fit? The only perfect squares less than 11 are 4 and 9.
December 8, 2015

math
If those are supposed to be exponents, try 110(0.70^x) and so on The base of the exponent is the rate of change. So, 1.2^x indicates a 20% growth rate. Now it should be simple to sort by rate of growth (as a percent, not an absolute $$ amount)
December 8, 2015

math
No, it's B! Why not show your work, so we can see what's going on? How did you evaluate .01 * 2^17?
December 8, 2015

math
Nope. You want f(17)-f(10) --------------- 17-10
December 8, 2015

algebra 2 trig
One way to do this is to set up coordinates. Let A = (0,0) B = (-9,0) When A has sailed 5 miles, it lies on the circle x^2+y^2 = 25 The line through B with slope 0.4877 is y = .4877(x+9) This line intersects the circle at two places: (-4.5,2.2) and (1.0,4.9) So, you gotta be ...
December 8, 2015

math
cost(1+.20) = 40
December 8, 2015

Algebra 1
If the walkway has outside length of x, the inside length (the side of the garden) is x-8 SO, the garden has area (x-8)^2
December 8, 2015

Math
The ratio of ages of P and Q in 1996 was 2:3 and in 2001 it was7:10 What will be the ratio in 2011? in 1996: P/Q=2/3, so Q=3P/2 in 2001: (P+5)/(Q+5)=7/10 (P+5)/(3P/2+5)=7/10 P=30 so, Q=45 In 2011, (30+15)/(45+15)=3/4
December 8, 2015

11U Functions Identity
-sinx - cosx*cotx -sinx - cos^2x/sinx (-sin^2x - cos^2x)/sinx -1/sinx -cscx
December 8, 2015

maths - incomplete
how far is she from the building? It appears to have been omitted.
December 8, 2015

Math
p(~rain) = 1-p(rain)
December 8, 2015

Trigonometry
where sinA = 0, cscA is not defined.
December 8, 2015

Calculus
when she is x meters from the light, and her shadow has height y, then 2/x = y/24 -2/x^2 dx/dt = 1/24 dy/dt When she is 2m from the building (22 m from the light), -2/22^2 * 0.6 = 1/24 dy/dt dy/dt = -0.06 m/s
December 8, 2015

Math
assuming you mean the dot product, and the 2.3 should be 2,3 then we have 2*4 + 3*3 = 17
December 7, 2015

physics
well, you know the equation of the altitude of the trajectory is y = x tanθ - g/(2 v^2 cos^2θ) x^2 So, just solve for θ in 12000tanθ - 9.8/(2(800cosθ)^2) = 3000 θ = 14° Better check my math.
December 7, 2015

Math
So, finish the diagram. If the man enters the water at point C, x meters upstream from A, and lands at point D, y meters downstream from B, then we have distances of land: (d^2+x^2) water: √(x+y)^2+d^2) land: √(y^2+(2d)^2) The time it takes to cross the river is ...
December 7, 2015

Math
if you can't answer that one, you have not read anything about the sine function. Just as a hint, remember that sin^2 + cos^2 = 1
December 7, 2015

Algebra
since distance = speed * time, 6(b+s)=90 10(b-s) = 90
December 7, 2015

st augustine/math
5x + 10(50-x) = 350
December 7, 2015

geometry
find the slope m of the line joining the two points. All parallel lines have the same slope m All perp. lines have slope -1/m Check out the point-slope form of a line.
December 7, 2015

Trig
square the previous equations and add them up. Recall that sin^2θ + cos^2θ = 1
December 7, 2015

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