Monday
January 16, 2017

Posts by Steve

Total # Posts: 47,908

PreCalc
every 10s the amount drops by 1/2, so m(t) = 5 * 2^(-t/10)
December 4, 2016

PreCalc
clearly, n(t) = 1500*(12000/1500)^t = 1500*8^t = 1500 e^(2.07944t)
December 4, 2016

Math
suppose I said 8 = r/4 How would you do that? Multiply by the denominator, right? So, r = Td Now divide by T to get d all alone: d = r/T
December 4, 2016

Math
We are talking about 7*24+1 = 169 hours. So, the clock loses 84.5 minutes in that time. ...
December 4, 2016

Math
depends on the coins.
December 4, 2016

Math grade 10
Just verify that they intersect at (3,3)
December 4, 2016

Maths
sorry. that's ?x-2?
December 4, 2016

Maths
y = 0.50 for x <= 2 0.50 + 0.10(x-2) for x > 2 technically, it is a step function, so y = 0.50 + 0.10⌈x-1⌉ for x > 2
December 4, 2016

Math
Just plug in your numbers. (a) H = 27.5 + 2.24*20 (d) 68 = 24+2.32F (e) as femurs lengthen, men grow more slowly
December 4, 2016

Maths
If the number is ab, then a = 2b 10a+b - 18 = 10b+a
December 4, 2016

Maths
a+b+c = 1000 a = b+120 b = c+110 b+120 + b + c = 1000 c+110+120 + c+110 + c = 1000 3c+340 = 1000 3c = 660 ...
December 4, 2016

Calculus
If the man's shadow has length s, then using similar triangles, when the man is x meters from the building, s/15 = 1.69/(15-x) s = 25.35/(15-x) ds/dt = 25.25/(15-x)^2 dx/dt Now plug in your numbers
December 4, 2016

Calculus
x^2+y^2 = 225 x dx/dt + y dy/dt = 0 now just plug in your numbers and solve for dy/dt
December 4, 2016

math
naturally, that would be 0.40 * 20, right?
December 4, 2016

Pre-calculus
These take some practice, but you soon learn the tricks of thinking... #1 r^2 = 4r cos? r = 4cos? #2 (r^2)^2 = 6(r^2 cos^2? - r^2 sin^2?) r^2 = 6(cos^2? - sin^2?) r^2 = 6cos(2?)
December 4, 2016

Math geometry
42
December 4, 2016

Pre-Calculus
This article should make things clear. Your function can be massaged to read r = -2/(1+3sin?) http://colalg.math.csusb.edu/~devel/IT/main/m11_conic/src/s08_polar-conics.html
December 3, 2016

Math, Quadratic Functions
xy = 108 x+2y = 30 x + 2(108/x) = 30 x^2 - 30x + 216 = 0 (x-12)(x-18) = 0 The yard is 12x9
December 3, 2016

Calculus
if n is even, r = a cos(n?) is a rosette with 2n leaves. Think about it. cos(n?) goes from 1 to 0 every time n? grows by pi/2. So, in [0,2pi], 6? goes in and out 12 times. You can always verify your work online, as at http://www.wolframalpha.com/input/?i=r%3D5cos(6%CE%B8)
December 3, 2016

algebra
The focus is (14,0) and the directrix is x=0 SO, you have a parabola opening to the right, with 2p=14, and vertex at (7,0) halfway from directrix to focus: y^2 = 28(x-7) http://www.wolframalpha.com/input/?i=parabola+y%5E2+%3D+28(x-7)
December 3, 2016

precalculus
your values for a,b,c are correct. However, your final answer is wrong, as you could have verified had you tried to check your answer. y = -1/2 x^2 + x + 6
December 3, 2016

maths(trigonometry)
You cannot mean 10A = 4/3 When you figure out what you mean, then just draw your triangle, and recall that sin? = y/r cos? = x/r
December 3, 2016

tss
the diameter is twice the radius: 10
December 3, 2016

Math
v = ?/4 * 0.5^2 * 100 = 25/4 ? ft^3
December 3, 2016

Math 10
20C3
December 3, 2016

History
Which is an impact of World War 1 A: German and Russian monarchies became stronger. B: The united states became the largest creditor nation. C: Europeans used their money to buy American goods. D: France no longer had a demand for British goods. My answer is B
December 3, 2016

Math
A prime number is a number whose factors are only 1 and itself like 17 is a prime number because it's only factors are 1 and 17. 25 is a composite number because it has other factors besides 1 and itself, 25. The factors of 25 are 1,5,and 25. That's why it's a ...
December 3, 2016

Math
well, 16/60 = 26.67% so, what % scored less?
December 3, 2016

intermediate algebra
well, it will double three times, right? So, that's 8 times the original amount...
December 3, 2016

Math
A man left 3/7 of his money to his wife, 1/2 of the remainder to his brother, and the rest he divided equally among his three children. If each of his children received $400, how much did his wife receive? starting with x, 3/7 went to wife, leaving 4/7 1/2 of that, 2/7, went ...
December 3, 2016

math
he spent the remainder of the 5 hours. That is, 5 - 2 3/10 = 2 7/10
December 3, 2016

Algebra
posting it again won't get it any more attention, especially after just 11 minutes! Just wastes your time and ours.
December 2, 2016

Algebra
8 - 3/4 c = 5 -3/4 c = -3 c = -3 * -4/3 = 4 check: 3/4 * 4 = 3 8-3 = 5
December 2, 2016

Math
well, these two angles add up to 90 degrees, right? So solve for x, and you can get the angle measures.
December 2, 2016

Math - Calculus @My bad.
Never mind. I rotated around the line y = -1.
December 2, 2016

Math - Calculus
The graphs intersect at (-4/3,32/3) and (1,6) We are only interested in x>0, so the volume is using discs v = ?[0,1] ?(R^2-r^2) dx where R=8-2x and r=6x^2 v = ?[0,1] ?((8-2x+1)^2-(6x^2+1)^2) dx = 782?/15 Since we are rotating around the line x = -1, the radius is increased ...
December 2, 2016

Math
using discs (washers), v = ?[0,3^(1/5)] ?(R^2-r^2) dx where R=3 and r=y=x^5 v = ?[0,3^(1/5)] ?(9-x^10) dx = 90?/11 3^(1/5) using shells, v = ?[0,3)] 2?rh dy where r=y and h=x=y^(1/5) v = ?[0,3)] 2?y^(6/5) dy = 90?/11 3^(1/5) You might have showed your work, right?
December 2, 2016

Pre-Calculus
tan?/sec? = tan?*cos? = sin? rsin? = 2 y = 2
December 2, 2016

Calculus
tan? = 4 ? = arctan(4) (C)
December 2, 2016

Calculus
plug and chug: 2xy = 3 2 rcos? rsin? = 3 so, (C)
December 2, 2016

Pre-Calculus
r = 4sec? r = 4/cos? rcos? = 4 x = 4
December 2, 2016

Pre-Calculus
recall that tan? = y/x so, your equation is just y/x = -?3 y = -?3 x
December 2, 2016

Calculus
your turn to show some work
December 2, 2016

Calculus
Since the region is rotated around x = -3, you should have ?((3+?(9-y^2))^2-9)
December 2, 2016

Calculus - Integrals
The curves intersect at (0,0) and (2?2,2?4) using discs, v = ?[0,2?2] ?(R^2-r^2) dx where R=?(4x) and r=x^2/2 v = ?[0,2?2] ?(4x-x^4/4) dx = 24??4/5 using shells, v = ?[0,2?4] 2?rh dy where r=y h=(y^2/4)-?(2y) v = ?[0,2?4] 2?y(?(2y)-(y^2/4)) dy = 24??4/5
December 2, 2016

algebra
actually, it's h(t) = 200 - 16t^2 so, use 11 for t and evaluate it.
December 2, 2016

Calculus
let f(x) = 4sinx, g(x) = 2cosx. the graphs cross at u=arctan(1/2), so the area is ?[0,u] (g-f) dx + ?[u,.7?] (f-g) dx
December 2, 2016

math
Since x>7, you want any number greater than 7. How hard is that? Only one choice fits.
December 2, 2016

Calculus
what's the trouble? The height of each small rectangle is just the distance between the curves, so a = ?[0,1] (2x^2-x^4) - (x^8) dx
December 2, 2016

algebra
look at the values for n n #people 0 4 1 4*3 2 (4*3)*3 = 4*3^2 ... n 4*3^n why do you repeat all the math? It's very distracting and annoying.
December 2, 2016

Maths
x-6 = (50-x)+12
December 2, 2016

Math
ab/2 = 12 a+b = 16
December 2, 2016

Math
already did! http://www.jiskha.com/display.cgi?id=1480652609
December 2, 2016

math
so, how many turns required for 1000m? 1000m * 1turn/2.2137m = ? turn
December 2, 2016

Algebra 1B
But it is not. Try again. It is A.
December 2, 2016

Algebra 1B
just solve for x when y=0. be careful, as A and D are almost the same
December 2, 2016

math
Drop an altitude from B to D on AC. Then triangles ABD and CBD are 30-60-90 right triangles. AD = DC = 3?3 so, AC = 6?3 a+b = 9
December 2, 2016

Math
well, the room is 4x3 tiles
December 2, 2016

Math
All are ok except #7 ?? and your answer formatting still sucks.
December 2, 2016

Check them please MAth
I don't see any of your answers to check. And your text formatting is totally bogus, D00d!
December 2, 2016

maths
Well 100% = 5/5 so, how many fifths are left?
December 2, 2016

Math
R*I = I ? is irrational I+I = I (usually) R^3 = R so ok there
December 2, 2016

Algebra
do you know the golden ratio?
December 2, 2016

algebra 2a solving systems using matrices
Nope. The matrix has no x in row 1.
December 2, 2016

Math
cos(180-x) = -cos(x) cos(90-x) = sin(x) so you have (0.5)cos^2(x)sin^2(x) = 0.05 cos^2(x) sin^2(x) = 1/10 sin^2(2x) = 1/40 sin(2x) = ±1/(2?10) ...
December 1, 2016

Pre-calc
one revolution covers 26? inches. Now let's start the conversion. 70mi/hr * 1hr/60min * 5280ft/mi * 12in/ft * 2?rad/26?in = 5686 rad/min
December 1, 2016

Math
200*20^2 = 200*400 = 80,000 if the answer is -8000 then there has been some mangling. It seems clear that something is wrong, since ()^2 is always positive.
December 1, 2016

math
Draw a diagram. The angle ? subtending the visible part of the earth is such that cos(?/2) = 1/3 see what you can do with that.
December 1, 2016

Algebra
visit here for all the details: http://www.mathportal.org/calculators/polynomials-solvers/synthetic-division-calculator.php
December 1, 2016

Algebra
try here: http://calc101.com/webMathematica/long-divide.jsp
December 1, 2016

deferential calculus
where is the wall? at the circumference of the courtyard?
December 1, 2016

math
standard form is just 9.26
December 1, 2016

math
9 + .2 + .06 = ...
December 1, 2016

Math
the quotient of x + 2 is incomplete. You need the quotient of ... and ... since division needs a divisor and a dividend.
December 1, 2016

Math
the areas are in the ratio 3^3:5^2 = 9:25 = 108:300
December 1, 2016

math
If it takes x hours, then 1/2 + 1/3 = 1/x
December 1, 2016

math seventh grade
well 550 = 5.5 * 100 so, it will take 100 minutes.
December 1, 2016

Math
sure, as long as you provide some work on your part. We don't like homework dumps here.
December 1, 2016

Math
7*18 + 4*14 + 26
December 1, 2016

math
3x-14 = 8 I suspect a typo. Is it reasonable for a kid to be almost 3 times as old as his grandfather?
December 1, 2016

Math
30/2.5 = 12
December 1, 2016

Algebra
4(6+x) = 6+x
December 1, 2016

Algebra
To fill the whole tank in x hours, 1/5 - 1/7 = 1/x but you only have to fill 1/3, so adjust accordingly.
December 1, 2016

steve plz help me on my math
just the reverse. The distributive property states that a(b+c) = ab + ac combining stuff inside the parentheses first does not involve the property.
December 1, 2016

math
huh. They gave you the formula, as well as the numbers. Just evaluate 1000 e^(-.028*50)
December 1, 2016

algebra 2
a=10 d=15 S6 = 6/2 (2a+5d)
December 1, 2016

maths
98*3 + x = 100*4
December 1, 2016

math algebra
just find t where 70*0.62^t = 10 .62^t = 1/7 t log.62 = log 1/7 t = log(1/7)/log(.62) = 4.07
December 1, 2016

Math adding fractions with distributive property
same as with any other distributive property problem: with: 6(1/2+2/3+3/4) 6(1/2) + 6(2/3) + 6(3/4) 3 + 4 + 4 1/2 11 1/2 without: 6(1/2+2/3+3/4) 6(6/12 + 8/12 + 9/12) 6(21/12) 21/2 11 1/2
December 1, 2016

math
If c is the hypotenuse, then a^2 + b^2 = 20 a^2+1=20 a = ?19 If not, then a^2 = b^2+c^2 = 1+20 = 21 a = ?21
December 1, 2016

maths
google alternating harmonic series = log(2) for many proofs and discussions, on different levels of math skills.
December 1, 2016

Math
for a square of side s, the diagonal is s?2 So, you have s?2 = 10 ...
December 1, 2016

Are All Right? Math
all are correct.
December 1, 2016

MATH
The area is a circle plus a cylinder, which can be thought of as a rectangle which has been rolled up.
December 1, 2016

Health
Sometimes a patient needs additional care that his or her regular physician cannot provide. In this instance, the physician can make a referral for a patient to see another physician. What are the three types of referrals? (1 point) regular, urgent, fast normal, fast, STAT ...
December 1, 2016

maths plz help
Whatever you copied and pasted from mangled the special characters. Try spelling out special stuff, such as sqrt() etc.
December 1, 2016

Math integer
-2(3 + -4 + -8 + 7) -2(-1 + -8 + 7) -2(-9 + 7) -2(-2) 4 -2(3 + -4 + -8 + 7) -2(3) + -2(-4) + -2(-8) + -2(7) -6 + 8 + 16 - 14 4 34 = -2(-17) so I'd be interested in how you got -17 from what's inside the parentheses.
December 1, 2016

algebra 1
f(m) = 12 - m/25
December 1, 2016

Math
If the average of the 21 students is x, then 21x + 78 + 93 = 23*75
December 1, 2016

Integral Calculus
since pi/4 = arctan(1) just plug in x=1 into the power series. That gives the actual series.
December 1, 2016

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