Friday
May 27, 2016

Posts by STEVE

Total # Posts: 40,845

Science
would that be Capt. Jack Sparrow?
April 15, 2016

math
You have a scaled-up 3-4-5 right triangle.
April 15, 2016

Percent error math
surely the change would be 5 * -3/2 = -15/2
April 15, 2016

maths
The question as stated has no solution. clearly the boys' %age is 80% of the girls'
April 15, 2016

Math
well, sin(2t) varies from -1 to 1.
April 15, 2016

Math Trig
correct. How can you be stuck there? Surely by the time you have learned trigonometry, you know how to work with fractions ... ? hint: 1 = 169/169
April 14, 2016

Algebra
j = 3g g = b/2 s = 2(j+b) s = 60 solving those, we get Greg is 6. So, Jane is 8.
April 14, 2016

Math
she rose 3*25 = 75 ft clearly she started up from -195-75 = -270 ft
April 14, 2016

Math
24:18 = 4:3
April 14, 2016

physics
surely you remember the first formula ever taught in physics: F = ma just plug in your numbers.
April 14, 2016

Math
Looks like 0.4 * 0.75
April 14, 2016

Precalculs
4x^2/36 + 49y^2/36 = 1 x^2/9 + y^2/(36/49) = 1 a = 3 b = 6/7 c^2 = a^2-b^2 = 9-36/49 = 405/49 c = 9√5/7 You found the vertices ok. They are at (±a,0) The foci are at (±c,0)
April 14, 2016

math
google is your friend. You can start here: http://mathforum.org/library/drmath/view/51708.html
April 14, 2016

Algebra
8n^2 - 6n + 7n^2 - 4n +5 8n^2+7n^2 -6n-4n + 5 15n^2 - 10n + 5 do the 2nd one the same way. Collect all the terms with the same powers, then add up the coefficients.
April 14, 2016

Polynomials
(m^2 – m + 3) + (m – 1) m^2-m+3+m-1 m^2-m+m+3-1 m^2+2 (4x^2 – 2x – 1) – (–3x^3 + 2) 4x^2-2x-1+3x^3-2 3x^3+4x^2-2x-1-2 3x^3+4x^2-2x-3
April 14, 2016

Help please
they are the numbers multiplying the variables. so, -4 is just a constant, not a coefficient. 5,2 are the coefficients.
April 14, 2016

Math - Please check!
they all look good to me.
April 14, 2016

Maths-equation
Try letting a = x+y b = y+z c = x+z Then you have a+b = 5ab b+c = 7bc a+c = 6ac Now see what you can do with that.
April 14, 2016

Math
The 1st alloy (x) is 2/5 iron and the 2nd alloy (30-x) is 7/10 iron. So, you want to mix 'em up so that (2/5)x + (7/10)(30-x) = (1/2)(30) x = 20 Check: 20 oz of Alloy 1 contains 8 oz iron 10 oz of Alloy 2 contains 7 oz iron. Total is 15 oz in 30 oz of the mix, or a ratio ...
April 14, 2016

Maths- Calculus
if you want the volume, that would be, using shells, ∫[0,∞] 2πrh dx where r=x and h=y=e^-x ∫[0,∞] 2πxe^-x dx = -2π(x+1)e^-x [0,∞] = 2π using discs, it is ∫[0,1] πr^2 dy where r = x = -ln(y) ∫[0,1] π(lny)^2...
April 14, 2016

Calculus
the volume would be ∫[-√5,√5] πr^2 dx where r=y=(5-x^2) Because of symmetry, that is 2∫[0,√5] π(5-x^2)^2 dx = 80π√5/3 using shells, that is 2∫[0,5] 2πrh dy where r=y and h=x=√(5-y) 2∫[0,5] 2πy√...
April 14, 2016

Algebra
this link is a nice long division calculator: http://calc101.com/webMathematica/long-divide.jsp
April 14, 2016

maths
Let the total distance be 2d. Then, since time = distance/speed, d/100 + d/90 = 1/3
April 14, 2016

Geometry
what is the "radius" of a square? Circles have a radius. Squares have a side and a diagonal.
April 14, 2016

Math
as with all polynomials, it is D
April 14, 2016

Solid Mensuration 04/15/16
since DE and BC are parallel, triangles ABC and ADE are similar. The ratio of sides of ADE to ABC = 28/70 = 2/5 So, CE = AC * 3/5 = 15 BD = AB * 3/5 = 9
April 14, 2016

math
what, never done a proof? (C)!
April 14, 2016

maths simultaneous equation
My previous solution of x=y=z=0 works, but was derived in error. The other solution is x = 5/24 y = 7/24 z = 1/24 x+2y+z = 5xy + 5xz + 5y^2 + 5yz x+y+2z = 7xy + 7xz + 7yz + 7z^2 2x+y+z = 6x^2 + 6xy + 6xz + 6yz Now just start substituting.
April 14, 2016

mathematics-combination vs A.P
n(n-1)(n-2)(n-3)(n-4)/5! - n(n-1)(n-2)(n-3)/4! = n(n-1)(n-2)(n-3)(n-4)(n-5)/6! - n(n-1)(n-2)(n-3)(n-4)/5! place all over a common denominator of 6! and then you have a polynomial of the 6th degree. Try a few easy values with synthetic division (0,1,2,3) and you can reduce the ...
April 14, 2016

Math
If he started with $x, then (1/5)(3/8 x) = 60 x = 800 After the spending he had left 800(1 - 5/8 - (1/5)(3/8)) = 240 why do you ask what it means? You presumably are calculating how much was left at the end.
April 14, 2016

math
http://www.learningace.com/doc/6138186/5b99373c5323a0518f25b611d97ade45/wallis-s-formula-to-integrate-powers-of-sine-or-sine-0-pi-2 is a good place to start. Try adjusting the interval to fit your needs.
April 14, 2016

Calculus 1
y' = b(1-ax)e^(-ax) 1-ax=0, at x=1/a = 4, making a = 1/4 y(4) = 4be^(-4/4) = 12 4b/e = 12 b = 3e y = 3ex e^(-x/4) verify this at https://www.wolframalpha.com/input/?i=y%3D3ex+e^%28-x%2F4%29
April 13, 2016

Calculus I
lim (√(ax+b)-9)/x = lim a/(2√(ax+b)) so, since we afre clearly dealing with lim = 0/0, we need √(ax+b) = 9 ax+b = 81 a/(2√(ax+b)) = 1 a = 2√(ax+b) a^2 = 4(ax+b) a^2 = 4*81 a = 18 so, b=81 lim (√(18x+81)-9)/x = 1 verify at https://www....
April 13, 2016

Math
so, plot a few points and draw the curve.
April 13, 2016

maths simultaneous equation
clearly x = -y = -z y = -z so, they are all zero.
April 13, 2016

math
horizontal: hexagon vertical: rectangle (pencil is unsharpened!)
April 13, 2016

Math
the slopes are Dixie: 20/60 = 1/3 Bell: 40/60 = 2/3 Liberty: 30/60 = 1/2 Bell is the steepest. Choice (A)
April 13, 2016

English
correction History*
April 13, 2016

English
1. Englishmen expected to have a ___ in their government. 2. The __ was the first legislature in the Jamestown colony. 3. The Massachusetts colonist legislature was the ____. 4. In Pennsylvania, England gave _____ to William Penn. 5. Even though the governor and large council ...
April 13, 2016

Geometry Honors
no deviation to that formula. Maybe you'd like the derivation... Draw a radius r, extended by h. Draw a second radius r. Connect the two endpoints, and that is the distance to the horizon. d = √((r+h)^2-r^2) = √(2rh+h^2) That's the distance in km. Usually h...
April 13, 2016

Math
a/(b+g) = 5/6 b/g = 2/5 g = b+36 b/(b+36) = 2/5 b=24 so, g=60 a/84 = 5/6 a = 70
April 13, 2016

Math
try using the letter x for the variable, not the multiply operator. Since all the choices are linear, check for the slope of the line. as x increases by 1, y increases by 3. So, look for y = 3x Now, if x=0, 3x=0, but y is 3. So, we need to adjust things, leaving the 3x alone: ...
April 13, 2016

math
Not enough to go on. Depending on the initial speed, the rocket could be almost anywhere, on its way up or down, at a variety of heights. If the initial speed was v, then you have the parabola and line y = -1.112/v^2 x^2 + 0.335x y = 0.662(x-1670) The value of v can change ...
April 13, 2016

Algebra. NEED HELP ASAP PLEASE
-65 <= F <= 60 -65 <= 9/5 C + 32 <= 60 -97 <= 9/5 C <= 28 -53.89 <= C <= 15.56
April 13, 2016

Math
for the quadratic, note that f(-1) = f(1) = 4 That means the vertex lies on the line x=0. y = a(x-0)^2 + c or, y = ax^2+5 Now use one other point to get a: 1 = 4a+5 a = -1 y = -x^2+5
April 13, 2016

Calculus
f(x) increases where f'(x) > 0. f(x) is concave up when f"(x) > 0.
April 13, 2016

Math
brute force way: n + n+2 + n+4 + n+6 = 296 using progressions: 4/2 (2n+3*2) = 296 In either case solve for n, and the next number is n+2
April 13, 2016

Maths
looks good to me, if all the cricket players also play football.
April 13, 2016

Maths
A set of n elements has 2^n subsets, including the empty set. So, if you have 4 fillings, and want at least one, that will allow for 2^4-1 = 15 different combinations, using 1 to 4 items. add in the totally plain one, and that gives 16 ways to make the sandwich. (not sand which!)
April 13, 2016

math
remember that the terms have a constant ratio, so (2k-28)/(k-6) = (k-6)/k Now just solve for k. You will get two answers, only one of which makes all the terms positive.
April 13, 2016

Integers
or, using what you know about arithmetic progressions, 6/2 (2a+5*1) = 171 a = 26 so the numbers are as shown above.
April 12, 2016

Math
Medi* comes off before taxes, so 22.48 + 52.72 + 0.23(1625.35-22.48-52.72) = 431.73
April 12, 2016

Math
just divide the deposit by the total: 175/625 = 0.28 = 28%
April 12, 2016

Math
well, g(1) = int{1,1} f(t)dt if the integral is done over an interval of zero width, its value is zero.
April 12, 2016

Math
just subtract the field from the total: (8x)(12x) - (3x)(6x) = 96x^2 - 18x^2 = 78x^2
April 12, 2016

Please HELP! Calculus (Implicit functions)
or, using implicit, 16x^2 - 8xy - x + y^2 = 0 32x - 8y - 8xy' + 2yy' = 0 (2y-8x)y' = 8y-32x dy/dx = (4-16x)/(y-8x) dx/dy = (√x+4x-8x)/(4-16x) = (1/4)(√x-4x)/(1-4x) Check my math and see whether these agree.
April 12, 2016

Please HELP! Calculus (Implicit functions)
switch variables and solve for y, and you get (after squaring) 16y^2 - (8x+1)y + x^2 = 0 y = [(8x+1)±√(16x+1)]/32 Pick the branch you want and take the derivative. Using the + branch, y' = 1/4 (1 + 1/√(16x+1))
April 12, 2016

Math
some kind of exponential would do it. So, with t as time since 1998, f(0) = 72000 f(2) = 70379 f(∞) = 60000 f(t) = 60000 + 12000 e^-kt now we need k so that f(2) = 70379 60000 + 12000 e^-2k = 10379 k = 0.073 So, f(t) = 60000 + 12000 e^(-.073t)
April 12, 2016

try,check,and revise
If Carly had c, the Rob had c-4. So, c + c-4 = 42 2c = 46 c = 23 So, Carly had 23 and Rob had 19
April 12, 2016

Calculus Help Stuck Part 2?
or, consider x-64 as the sum of cubes: x-64 = (∛x)^3 - 4^3 so it factors into (∛x-4)(∛x^2+4∛x+16) Now the fraction is just 1/(∛x^2+4∛x+16) = 1/(16+16+16) = 1/48
April 12, 2016

Calculus Help Stuck Part 2?
(∛x-4)/(x-64) -> 0/0 so try L'Hospital's rule. Then the limit is (1/(3∛x^2) / (1) = 1/(3*16) = 1/48
April 12, 2016

try,check,and revise
27+3x
April 12, 2016

math
(1-2i)(1+2i) = 1^2+2^2 = 5 (1-i)(1+i) = 1^2+1^2 = 2 5*2 = 10
April 12, 2016

algebra/math
surely you have learned how to solve a quadratic equation, or you'd not have been given this exercise. x^2+6x + 9 = 24 x^2+6x-15 = 0 x = (-6±√96)/2 = -3±2√6 clearly, -3-2√6 is less than -3+2√6
April 12, 2016

algebra
since (a-bi)(a+bi) = a^2+b^2, we have (15-20i)(1+2i) ------------------ (1-2i)(1+2i) = (15-20i+30i-40i^2)/(1^2+2^2) = (55+10i)/5 = 11+2i
April 12, 2016

Math
well, solve the equation and pick the smaller value. I hope you are not expecting integers.
April 12, 2016

math
well, (x + 7/2)^2 = x^2 + 7x + 49/4
April 12, 2016

Trigonometry
draw a diagram. Then it will be clear that your distance x can be found by 1200/x = sin32°
April 12, 2016

Graphs
The points on f(2x) are half as far from the y-axis as those of f(x)
April 12, 2016

Math
depends on the shape of the volume, eh?
April 12, 2016

math
see whether you get what wolframalpha does: https://www.wolframalpha.com/input/?i=solve+%28x-2%29^2+%2B+%28y-7%29^2+%3D+169,+x-2y%3D10
April 12, 2016

math
all points (x,y) that are 13 units away from the point (2,7) defines a circle: (x-2)^2 + (y-7)^2 = 169 so, the line x-2y=10 may intersect the circle in 0,1, or 2 points. So, plug x=2y+10 into the equation of the circle and see where the two graphs intersect.
April 12, 2016

math
well, they intersect where f(x) = g(x). x^3-x^2+x+1 = x^3+x^2+x+1 -x^2 = x^2 x = 0 to check, see https://www.wolframalpha.com/input/?i=x^3-x^2%2Bx%2B1+%3D+x^3%2Bx^2%2Bx%2B1
April 12, 2016

Math 142 (Pre-Cal) (Circles)
the circumference is 2pi*10 = 62.83cm So, multiply that by the number of times the wheel turns in 15 seconds.
April 12, 2016

Math/geometry
since the angles x and y are complementary, x+y = 90 y = 3x+6 now just solve for x and y.
April 12, 2016

Geometry
since the circle has area πr^2, and the sphere has surface area 4πr^2, what do you think?
April 12, 2016

Algebra
A linear equation is y=mx+b where x is the sales, b is the base pay, and m is the percentage used to find the commission. We have 560 = m*800 + b 460 = m*460 + b 540 = m*540 + b 600 = m*1000 + b Those points do not fit any linear equation. Check for typos.
April 12, 2016

Maths Ms sue
300+10+16+22+... = 310 + 19/2 (2*16 + 18*6) = 1640
April 12, 2016

math
can you not check your answers? (-4,8) works (5,35) works
April 12, 2016

Geometry - incomplete
No idea where CDE are in relation to BGF. All you have said is that the two squares share corner A. However, you do know that the smaller square has sides 1/2 as long as the larger one, so its area is 1/4 as big. I suspect you can use that to determine the shaded area. Also, a...
April 12, 2016

Algebra 1
Who needs a teacher? Just think a bit. Where is the ball to start with? At the top of the cliff. That's when t=0. So, plug in 0 for t and evaluate.
April 12, 2016

math
they all express a ratio, but I'd guess C is least likely to be used.
April 12, 2016

Math
can't quite parse your text. It's probably one of 976 + 2n or 9762n
April 12, 2016

Math
if the angle is x, then it is opposite the shortest side. tan(x) = 5/8
April 12, 2016

Math
P(blue) = 3/12 * 2/11 P(>= 1 blue) = 1-P(no blue) = 1 - (9/12 * 8/11)
April 12, 2016

algebra. someone please explain to me please!
since time = distance/speed, d/12 + d/6 = 6
April 12, 2016

Pre calculus
what about the uphill anchor point? I assume the antenna is vertical. Anyway, if the uphill anchor point is x feet from the base, then we have uphill cable length is u, where u^2 = x^2+100^2 - 2*100x cos 78° downhill cable length d is d^2 = 95^2 + 100^2 - 2*95*100 cos102°
April 12, 2016

algebra
900 + .07(x-1000) = 2900
April 12, 2016

Basic math
5ml/4hr * 14days * 24 hr/day * 1floz/29.57ml = 14.20 floz
April 12, 2016

Math Check my Answers please ?
good work. both correct.
April 12, 2016

Math
I like C, but it rises 3 ft for every 4 ft of horizontal travel. Double-check the table and the questions. If D says it rises 3/4 ft or 9 inches, then D is your choice.
April 12, 2016

Math
4^4 * 4^6 = 4^(4+6) = 4^10 you add exponents, since what you are really doing is just short for 4x4x4x4 x 4x4x4x4x4x4 = 4x4x4x4x4x4x4x4x4x4 just as multiplication is short for 4x4 + 4x6 = 4x(4+6) 4+4+4+4 + 4+4+4+4+4+4 = 4+4+4+4+4+4+4+4+4+4
April 12, 2016

math
a = l*w a = (w+3)(w) = w^2+3w
April 12, 2016

math
25,10,10,5,5,1
April 12, 2016

math
(n+3)^2 = 25 n+3 = -5 n = -8
April 12, 2016

Algebra
Just use the quadratic formula, which you learned in Algebra I: t = -233±√(233^2 - 4(-16)(48)) --------------------------------       2(-16) t = (233±√57361)/32 or, t = -0.20 or 14.76 We don't allow negative time, so ...
April 12, 2016

Algebra
it hits the ground, naturally, when h=0. So, just find t when -16t^2 + 233t + 48 = 0
April 12, 2016

Math
If you bisect the first chord with a radius, you will have a right triangle with sides 15 and 20. So, the hypotenuse (another radius) is 25. Now, draw the second chord, and its triangle is 7-24-25, so the full chord is 14 cm long.
April 12, 2016

Algebra
x^2-9x+14 = 0 x^2 - 9x + (9/2)^2 = -14 + (9/2)^2 (x - 9/2)^2 = 25/4 x - 9/2 = ±5/2 x = 9/2 ± 5/2 x = 2 or 7
April 12, 2016

science
if 1/4 remains, that means 2 half-lives have passed.
April 12, 2016

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