Friday
December 9, 2016

Posts by Steve

Total # Posts: 47,031

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

Algebra
1,2 ok 50 is 62.5% of 80
December 1, 2016

Math check my answers
all correct.
December 1, 2016

Algebra
product, not sum better review what that means.
December 1, 2016

Algebra 2
Having n in the index and in the expression is bogus. If you mean n-1 ? (3k-2) k=1 Then that can be split up into ?3k - ?2 Now, ?2 is 2(n-1) ?3k = 3?k You know that n ?k = n(n+1)/2 k=1 So for you example, 3?k = 3(n-1)(n)/2 The final sum is thus 2(n-1) + 3(n-1)(n)/2 If I ...
December 1, 2016

Math
x values change sign. y stays the same try experimenting with this -- it should be quite clear.
December 1, 2016

Calculus
(a) is correct (b) solve for t when h=0 (c) use the above t to get v
December 1, 2016

Gk
sounds like a cheap pair of glasses...
December 1, 2016

Math
524 - 520
December 1, 2016

calculus
g has a critical value where g'=0: x = ±4 max/concave down if g" < 0 g" = (x^2-4x+16)/(x-2)^2 For the tangent line, you have a point (3,4) and a slope (-7), so the line is y-4 = -7(x-3)
December 1, 2016

Math
23 years before Columbus set sail. or, maybe 11 14 16 19 ...
December 1, 2016

Math
You now have expressions for AN and NC Using the law of cosines, AN^2 = CN^2 + 2^2 - 2*CN*2 cos?ACN
December 1, 2016

Math
an angle is in degrees, not feet. Your height h is found via h/80 = tan70°
December 1, 2016

math
surely you can tell which is the greatest odd digit. Just take it from there.
December 1, 2016

Algebra
Fix the typo Then just expand and subtract, knowing that (x-4)^2 = x^2-8x+16
November 30, 2016

Algebra
w(3w-2) = 60 solve for w, then get length
November 30, 2016

Calculus
just find c such that 3c^2 = (65-9)/(4-2)
November 30, 2016

Algebra 1
double the 1st equation and you have 6x + 2y = -22 6x - 2y = -2 Now you can add them to eliminate y, or subtract to eliminate x.
November 30, 2016

Math
g = b+12 b/(b+g) = 35/100 ...
November 30, 2016

calc
since C = 2?r, dC/dt = 2? dr/dt Since dC/dt = ?/4, dr/dt = (?/4)/(2?) = 1/8 cm/min v = ?r^2h dv/dt = 2?rh dr/dt + ?r^2 dh/dt = 2?*4*12*(1/8) + ?*16*(1/2) = 20? cm^3/min
November 30, 2016

Pre-Calculus
r can be anything. So, the equation is just a straight line at that angle. tan? = -?3 y/x = -?3 ...
November 30, 2016

Math
add up the value of all the coins: 5n + 10(n+15) = 255
November 30, 2016

Math -Calculus
you need to do a definite integral. So, what are the limits? The curve intersects the x-axis at x = ±?(3/2) so now all you have to do is evaluate 6x - 4/3 x^3 at those points. Due to symmetry, you can just take twice the value from 0 to ?(3/2) f(?(3/2)) = 6?(3/2) - 4/3...
November 30, 2016

Algebra
If he makes x more cheese sandwiches, then (12+20+4+x) = 5(4+x) x = 4 check: 4+4=8 cheese out of 40 total. You can try other settings as well.
November 30, 2016

Math (Geometry)
well, if x is the number of hours worked, and y is the pay, y = 320 if x <= 40 8x if x > 40 It's a piecewise function, since it changes at x=40 hours
November 30, 2016

Algebra
no question. But there will be a guaranteed pay of 8*40 = $320
November 30, 2016

Math
If x>0, 4x > 5*2 x > 5/2 If x<0, 4x < 5*2 x < 5/2 But x<0, so x < 0 < 5/2 is a solution. Naturally, since if x<0, 2/x < 0, so 4/5 > 2/x for any negative x.
November 30, 2016

6th grade math
well, 30 = 6*5, so five times as far.
November 30, 2016

Algebra
from the axis and vertex, we know y = a(x+2) - 6 Now use the point to solve for a. You already know that a is positive (why?)
November 30, 2016

Pre-Calculus
C depending on how the equations are set up. Position involves x and y, and both depend on the time t.
November 30, 2016

Math - Aglebra One (Ratios)
If there are d dollars and h halves, then what do we know? d = h+133 d/h = 5/2 Now you can easily find h and d.
November 30, 2016

precalculus
man, this has been an agonizingly slow homework dump. Absolutely no work shown on your part, and general questions that indicate a total lack of preparation or study.
November 30, 2016

College alegbra
If the field has length x and width y, then xy = 1500 y = 1500/x p = 2x+3y = 2x + 4500/x See what you can do with that.
November 30, 2016

Super Hard Math
2*9 + 5*9 = (2+5)*9 = 7*9 did you actually try using some arrays?
November 30, 2016

Math
the height difference is 15 ft. So, now just use the Pythagorean Theorem for a triangle with legs of 15 and 36 Hint: Recall that one of your standard right triangles is 5-12-13
November 30, 2016

Calculus
exponentials grow and decay faster than polynomials. So, b,d -> 0 logs grow more slowly than polynomials, so c -> 0 a does not go to zero, since f(x)g(x) = 2x^2 + x/5 e^-x -> 2x^2
November 30, 2016

Math
so, if x is the number, what is one half of the number ?
November 30, 2016

Calculus
if you google MVT you will see diagrams of what it means. All it amounts to is that if the conditions are met, there will be one or more places in the interval where the tangent line is parallel to the line joining the points at the ends of the interval. In this case, the line...
November 30, 2016

math
with a little practice, which you evidently have, you can just read it from the equation, since b^0 = 1 for any nonzero b. But, when the function is a little more complicated, you may have to plug in t=0 and evaluate a more involved expression. Read about Newton's law of ...
November 30, 2016

Math
no. A is -6-24
November 30, 2016

geometry
6 * 8 * sin45°
November 30, 2016

Math
y=kx so, y/x = k is constant. You want y such that y/9 = 15/5 You don't really need to know what k is.
November 30, 2016

math
well, 2+3+4 = 9
November 30, 2016

Math
difference, not product
November 30, 2016

math
T-C = ((40-4t)-(-10+45t),(20+75t)-(40+70t)) = (50-49t,-20+5t) at t=0, then d=|T-C| = ?(50^2+20^2) = ?2900 = 53.9 d^2 = (50-49t)^2 + (-20+5t)^2 = 2426t^2 - 5100t + 2900 Not sure how you got your expression
November 30, 2016

precalculus
Your answer gives x = -1 y = -3/2 z = 1 but these do not satisfy the original equations. I already gave you a url which shows the row-echelon details.
November 30, 2016

pre calculus
the equation fits. Could you not do as I did, and just plug in t=1,2,3 to see that the result is as desired?
November 30, 2016

Maths
AC = AB+BC = 3+4 = 7 AC/CD = 2/1, so CD = 7/2 AD = AC+CD, so BC/AD = 4/(7 + 7/2) = 8/21
November 30, 2016

Algebra
The nth row, Rn = 41-4(n-1) = 45-4n So, there are 11 rows, since 45-48 < 0 You have an AP with a = 41 d = -4 S11 = 11/2 (2*41 + 10(-4)) = 231
November 30, 2016

Algebra
This is easy if you just break it up: 8 ?(-1)^k + 1.5k 1 = ?(-1)^k + ?1.5k The first sum is -1+1-1+1... = 0, so = ?1.5k = 1.5 ?k Now you know that n ?k = n(n+1)/2 1 so, your sum is just 1.5* 8*9/2 = 54
November 30, 2016

Calculus 1
the area of the water's surface is 4? m^2 since volume = area * thickness, the thickness is changing by 2/(4?) = 1/(2?) m/min
November 30, 2016

college
it must show all debits and credits, and they must all add up to the same value.
November 30, 2016

Calculus MATH
it's just a step function, so just add up the areas of the rectangles with heights 0,1,2,...9 and width 0.1
November 30, 2016

math
If you mean ?54 * 3i then that is 3?6 * 3i = 9?6 i ?(54*3)i = 9?2 i
November 30, 2016

college algebra
1/x = 1/60 + 1/55 x = 660/223 So, it will take them about 28.7 minutes. Sounds right, since their times are so close, it would just about cut the time in half, working together.
November 30, 2016

Calculus
A is true, since (0,1) is an open interval. Pick any nonzero x, and the limit from both sides is just 1-x. B and D are also true. C is false, since f(0) = 0 and f(x)->1 as x->0+ f is continuous on (0,1] There is a problem with the definition. It should be f(x) = 0 if x=0...
November 30, 2016

precalculus
for the row echelon stuff, enter your data here to check your results: http://www.math.odu.edu/~bogacki/cgi-bin/lat.cgi 2-7 look ok #8 is missing data, but the equation looks typical. Must be for a flight from ground level at 64 ft/s
November 30, 2016

Calculus
a is ok, since it is differentiable on (-1,1). It has a vertical tangent, bot only at the endpoint(s). b is ok for the same reason c is ok d is real on the interval, since it's ?(x+1), so it's ok too Looks to me like they all work, since the MVT requires 1. f(x) is ...
November 30, 2016

pre calculus
enough of these. Lots have been done, and a url provided.
November 30, 2016

additional mathematics
just use the formulas you know: a+d = 15 a+3d = 23 Note that T2 and T4 differ by 2d=8.
November 30, 2016

math
If you draw the diagram, you can see that you have a right triangle with 45° angles. So, the two legs are the same length: 60km.
November 30, 2016

Math
I think they want you to approximate it with the Taylor series, which involves y", y"', etc.
November 30, 2016

Math - good catch
thanks. leftover from a previous attempt.
November 30, 2016

Math
The volume of a spherical cap of radius r and height h (the water depth) is v = ?/3 h^2(3r-h) = ?/3 h^2(30-h) = ?/3 (30h^2 - h^3) dv/dt = ?(20h - h^2) dh/dt Now, when is h increasing most slowly? When the water surface area is greatest (since dv/dt is constant, and dv = a*dh) ...
November 30, 2016

cal
v = 10xy dv/dt = 10(y dx/dt + x dy/dt) So, using your numbers, dv/dt = 10(8(-4) + 6(2)) = -200 looks good to me.
November 30, 2016

cal
good call. So, rather than being where f' goes negative, it is where f' starts decreasing: where f" goes negative. That is, when the graph changes from concave up to concave down. Unfortunately, this graph starts out concave down, so the growth rate is always ...
November 30, 2016

cal
well, what does diminishing returns mean? Sales decrease while numbers increase. So, you want to find t for max N.
November 30, 2016

cal
f = 4x^3-21x^2+36x-4 f' = 12x^2 - 42x + 36 = 6(2x^2-7x+6) = 6(2x-3)(x-2) f" = 24x-42 = 6(4x-7) f is concave up for x > 7/4 f is decreasing for x in (3/2,2) So, both for x in (7/4,2) f has a max at x=3/2, so it cannot be concave up there.
November 30, 2016

math
what do you mean by one of the line of ax2+2hxy+by2=0 ?? That is a conic section, unless it's degenerate. In that case, you have (ax+c)(x+d)=0 ad+c = 2h cd = b Now work with the slopes of the lines, using the condition that one is twice the other.
November 30, 2016

Math
You sure there are no typos? I suspect you want (sinx+siny)/(cosx+cosy) Anyway, you can get things a bit simpler by taking the tan of both sides, since tan(arctan(x)) = x also, tan(x/2) = (1-cosx)/sinx
November 30, 2016

Math Logs
raise both sides as powers of 4, and you have, since 4^log_4(u) = u x+5 = 64(x-2) 63x = 133 x = 19/9
November 29, 2016

math
you want P where Pe^(.065*4) = 3000
November 29, 2016

precalculus
since (0,3) and (2,3) have the same y-value, the vertex is at x=1. So, (1,4) is the vertex, and we have y = a(x-1)^2 + 4 At x=0, a(1)+4 = 3 a = -1 y = -(x-1)^2 + 4 = -x^2+2x+3
November 29, 2016

precalculus
If you have to ask such a general question, you must not have read the relevant section in your text. So, you can start here: https://en.wikipedia.org/wiki/Row_echelon_form
November 29, 2016

precalculus
I get 2/x - 1/(x-1) + 2/(x-1)^2 what do you get?
November 29, 2016

algebra
m = (-5-(-10))/(-2-(-9)) = 5/7
November 29, 2016

Calc
what's the comma for? anyway, d/du arcsec(u) = 1/(x?(1-x^2)) the ?(x^2-4) I'm sure you can handle.
November 29, 2016

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