Tuesday
February 9, 2016

Posts by steve

Total # Posts: 37,504

Geometry
start with the two-point form and then just rearrange things as needed y-5 = (5-1)/(6+3) * (x-6)
December 15, 2015

Algebra 2
one way: just list the terms: 15,20,25,30,35,40 now add 'em up. Or, recognize this an an A.P. with a=15 d=5 and you want to sum the first 6 terms: S6 = 6/2 (2*15+5*5) = 165
December 15, 2015

Algebra 2
You have a sequence with a = 6*2^1 = 12 r=2 So, you have S10 = 12 * (2^10-1)/(2-1) = 12276
December 15, 2015

Algebra 2
school starts out 6.8 miles away, and the distance decreases with each hour. So, y = 6.8 - 4.2x
December 15, 2015

math
You can play around with Z table stuff here: http://davidmlane.com/hyperstat/z_table.html
December 15, 2015

math
cost: 250 sales: 1.75*100 = 175 Now you can get the difference cost: 56 sales: (24-6)g 18g = 56-20
December 15, 2015

maths
2x/5+3y/4=5 3x/10+5y/8=8 Fractions are usually messy, so let's get rid of them: 8x+15y = 100 12x+25y = 320 For substitution, note that 12x = (3/2)(8x), and since 8x = 100-15y, (3/2)(100-15y)+25y = 320 Now you can find y, and then x. For elimination, let's eliminate y, ...
December 15, 2015

Math
make sure the amount of drug adds up: 7(30-x) + 0x = 2(30)
December 15, 2015

geometry
Well, the figure has six faces, 4 of which are lateral. So, the remaining two faces have an area of 14 m^2. So, the base must have an area of 7 m^2.
December 15, 2015

Math
is 0 some kind of operation? And is o some kind of number?
December 15, 2015

math
why complete the square? 24x+3 = y^2-6y 24x = y^2-6y-3 x = 1/24 y^2 - 1/4 y - 1/8 That's standard form. To complete the square, you'd do y^2-6y = 24x+3 y^2-6y+9 = 24x+3+9 (y-3)^2 = 24x+12 24x = (y-3)^2 - 12 x = 1/24 (y-3)^2 - 1/2 Looks like you need to review your text...
December 15, 2015

math
well, $18 is 3 times as much as $6, so you can buy 3 times as much candy, right?
December 15, 2015

Math
t10 = t1 + (t13-t1)/(13-1) * (10-1)
December 15, 2015

Chemistry
since PV=kT, PV/T is constant. So, you want P such that P(6.5)/500 = (1)(4.05)/273
December 15, 2015

punjab technical university
You sure you're ready for the university? You cannot seem to (a) properly name your subject (b) completely post the problem
December 15, 2015

MAths
If the vehicle drives to a point x km from the "nearest point" then the distances are terrain: √(30^2+x^2) road: 70-x So, the time is √(900+x^2)/30 + (70-x)/180 Now just find where that has a minimum. I get x≈5km
December 15, 2015

math
with a circle of diameter d, half the circumference is πd/2. So, what's the difference between πd/2 and d? Now plug in your numbers.
December 15, 2015

math
not sure why you'd want to maximize the costs, but the initial steps are the same. Box has sides of x, and height y. We know that x^2y = 40, so y = 40/x^2 So, the cost is c(x) = 2*2*x^2 + 1*4*xy = 4x^2 + 160/x I think you can see that there is no maximum value, so now just...
December 15, 2015

Math
first, g must be continuous g(0-) = (0+1)^2 = 1 g(0+) = 2*0+1 = 1 g(3-) = 2*3+1 = 7 g(3+) = (4-3)^2 = 1 so, g is continuous at x=0, but not at x=3. g'(0-) = 2x+2 = 2 g'(0+) = 2 So, g is differentiable at x=0, since the slope is the same from both sides. So g is ...
December 15, 2015

maths
(2*4)/8 * 5 2*4-8+5
December 15, 2015

geometry
please include the lost information.
December 15, 2015

Algebra
c can have an infinite number of values. 2x^2+5x+c can be (2x+1)(x+2) if c = 2 (2x-1)(x+3) if c = -3 and many more.
December 15, 2015

Algebra
1C 2A 3D (multiply by 5, not add) 4C Not too bad.
December 15, 2015

Math
12x-40=200
December 14, 2015

algebra
If x kg of almonds, then we have 1.20*x + 1.50*180 = 1.28(x+180)
December 14, 2015

helping sons math
(2 cents/3 cans) * 2187 cans = 1458 cents
December 14, 2015

Math
you have a sequence where a = 0.1 r = 1.0077 Now you can write the formulas needed.
December 14, 2015

Calculus
I mean, the rate at which the radius is increasing.
December 14, 2015

Calculus
draw a diagram. We have at a depth of h feet, a water surface with a diameter of h feet. So, h=2r v = 1/3 π r^2 h = 2π/3 r^3 dv/dt = 2πr^2 dr/dt so we have 9 = (2π)(4) dr/dt Now you have dr/dt, the rate that the water is rising.
December 14, 2015

Math
There are 16 possible rolls. So, how many of those total to 5?
December 14, 2015

Math
y can be anything. It is unrelated to x.
December 14, 2015

Math
well, if each pitcher holds 1/4 gallon, how many pitchers are there in a whole gallon? Then multiply that by the number of gallons...
December 14, 2015

MATH ASAP
Don't come rushing in here expecting someone to be waiting to give you an answer ASAP. We help when we see the problems. You do know that one yard is 3 feet, right? So, just multiply that by the number of yards. If you do it right, you will get 30 1/2.
December 14, 2015

Algebra
Don't know the choices, but one equation is .18(11) = .12(11+g)
December 14, 2015

Algebra
since distance=speed*time, (p-w)(2.5) = 400 (p+w)(2) = 400 Now just solve for w, the wind speed.
December 14, 2015

Math (help soon)
m/k = 12/7 k-32 = 5/7 k 4/7 k = 32 k = 56 m/56 = 12/7 m = 96 Now you can answer the questions
December 14, 2015

Math Order of operation
Just write the expression in the order you learn the facts: Adam has $450: 450 He spends $210: 450-210 he divides all the money into four parts and one part he keeps: (450-210)/4 Here you need the parentheses, because 450-210/4 means that only the 210 is divided into 4 parts. ...
December 14, 2015

Math
Did you actually draw the lines? The area enclosed is a trapezoid with height = 8 top base = 3 bottom base = 7 So now you can get the area
December 14, 2015

Geometry 12
Gotta tell me where F is. You do know that ABDE is a rectangle.
December 14, 2015

Geometry 12
If one base angle is 42, so is the other. And, the three angles total 180. The length of the sides does not matter.
December 14, 2015

math
2 of the 6 numbers are less than 3. So, is the die loaded?
December 14, 2015

Algebra
you know there is a fixed cost. So, start out with C(n) = 43.50 Now, that does not depend on n. What does? The number of pizzas. Each costs 4.50, so the total cost of the wages is 4.50n C(n) = 43.50 + 4.50n Easy as (pizza) pie, right?
December 14, 2015

MATH
add up the values. If there are n nickels, then they coins are worth 5n + 25(n+24) = 1110
December 14, 2015

math
cost c(x) = 3.21*m(x) revenue r(x) = x*m(x) profit p(x) = r(x)-c(x) Now go for it.
December 14, 2015

math
For A, the terms are a,ar,ar^2,ar^3,... For B=1/A, the terms are 1/a, 1/(ar), 1/(ar^2), ... = (1/a), (1/a)(1/r), (1/a)(1/r)^2, ... For sequence B, the 1st term is 1/a, and the common ratio is 1/r. So, it's also a G.P.
December 14, 2015

Math
I agree.
December 14, 2015

Science HELP PLZ
They all look correct to me, except I think #6 is B.
December 14, 2015

Algebra 2 (Math)
If you have no clue, then clearly you have not studied your material, since it must have been covered. If a parabola has vertex at (h,k), then the equation is y = a(x-h)^2+k You have y = -x^2+12x-4 = -(x^2-12x) -4 Now recall that (x+n)^2 = x^2+2nx+n^2 That means that you have ...
December 14, 2015

Algebra 1
clearly, f = 20+30h
December 14, 2015

Algebra
the still-air speed is the average of the other two speeds, since the same amount is added or subtracted to get the final air speeds.
December 14, 2015

Mathematics
so, did you try the rule? why not show what you got? If y = u/v, where u and v are functions of f, then y' = (u'v - uv')/v^2 In this case, that means y' = {(1)(cosx) - (4+x)(-sinx)]/(cosx)^2 At x=0, y = (4+0)/(1) = 4 y' = [(1)(1)-(4)(0)]/1^2 = 1 So, the ...
December 14, 2015

math
frequency: 2*8=16 area: 4*80=320
December 14, 2015

Mathematics
so, assuming that you want to find x where (2+x)(-sinx) = 0, then you must have either 2+x = 0 or -sinx = 0 I expect you can solve both of those. This shows why we always set the product of factors equal to zero. If a product is zero, then at least one of the factors must be ...
December 14, 2015

math
Here is a related question. A man left his house and walked 5 miles south, then 5 miles east, then 5 miles north, at which time he was back at his house, and a bear was trying to get in. What color was the bear?
December 14, 2015

multiplication
42
December 14, 2015

Math
well, for any A.P., the nth term, Tn is Tn = a + (n-1)d So, plug in your numbers.
December 14, 2015

Math
Recall that Sn = n/2 (2a+(n-1)d)
December 13, 2015

plane geometry
recall that the area of a segment is a = 1/2 r^2 (θ-sinθ) If the longest chord is c, then (c/2)/r = sin(θ/2) So, now we have 27.5 = r*sin(θ/2) 330 = 1/2 r^2 (θ-sinθ) Solve those two and you have θ = 1.24 so, r = 47.33 as always, check my math
December 13, 2015

Pre-Calc, please a.s.a.p!!
(a) as with all parabolas, max height at t = -b/2a = 304/32 (b) max height is d(304/32) (c) find the roots of d(t)=500. d(t)>500 between the roots. (d) hits ground at d(t) = 0. t=304/16 Don't forget what you know about parabolas from Algebra I.
December 13, 2015

Math
If they cost $n and $w per yard, then we have 14n+20w = 1738 16n+25w = 2102 Now just solve for n and w.
December 13, 2015

math
the cost for the parts must add up to the cost for the mix, so r+n = 40 4r+6n = 4.75*40
December 13, 2015

Math
f1(0) = 2 f2(0) = 2 So, f is continuous. If a tangent exists, the slope from the left must be the same as the slope from the right. f1'(x) = -2-2x f2'(x) = 2 f1'(0) = -2 So, there is no tangent. You can see this from the graphs below. They touch at (0,2), but the ...
December 13, 2015

maths
That would be 1*P(1red)+2*P(2red)+3*P(3red) Now just figure the probabilities of drawing 1,2 or 3 red balls.
December 13, 2015

Math
v = ds/dt = 32.2t
December 13, 2015

Math
just define f(-2) to be some value other than its limit. f(x) = 2x for x ≠ -2 f(-2) = 0 The limit exists from both sides, but f is not continuous there.
December 13, 2015

calculus
Does ^3square root mean cube root? I'll assume so. Roots are just fractional exponents, so y = 7x arcsin(2x)+(1+4x^2)^(1/3) recall that d/dx arcsin(u) = 1/√(1-u^2) du/dx, so Now, using the product rule, y' = 7 arcsin(2x) + 14x/√(1-4x^2) + (1/3)(1+4x^2)^(-2/...
December 13, 2015

Inequalities
-x/3 - 5 < 12
December 13, 2015

History
how long can the treasurer of the united states serve?
December 13, 2015

Math
so, did you use MATLAB?
December 13, 2015

Trigonometry
The height h of the tree is given by h/10 = tan 65° Now, having h, you can get the distance f of the firefighter: f/h = cot 50° Now, the distance d between the dog and the firefighter is d^2 = 10^2+f^2
December 13, 2015

Tilili
(A+B)x(A-B) = AxA + BxA - AxB - BxB = BxA - AxB = -2(AxB) But, AxB is a vector, not a scalar. You have a glitch in there somewhere.
December 13, 2015

Calculus
nope. Look up arc length for parametric curves. ds^2 = (dx/dt)^2 + (dy/dt)^2 The distance traveled is the arc length.
December 12, 2015

math
.04x = .03(10000-x)+246
December 12, 2015

Math Help!
if b=2a, then a^2 + (2a)^2 = 1 5a^2 = 1 a = 1/√5 similarly for a=2b
December 12, 2015

delta prep (physics)
conserve momentum .27*200 = 4.1v
December 12, 2015

Function plz help!!!
How about starting with the definition of the equation? ∇^2(u) = 0 ∂u/∂x = 1/(1+y^2/x^2) (-y/x^2) = x^2/(x^2+y^2) (-y/x^2) = -y/(x^2+y^2) ∂^u/∂x^2 = 2xy/(x^2+y^2)^2 Now do ∂u/∂y and then form the equation.
December 12, 2015

geometrie
one side is the horizontal line from (4,5) to (9,5). It is clearly 5 units long. So, the other parallel side is also 5 units long, starting at (5,1)...
December 12, 2015

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

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