Monday
February 20, 2017

Posts by STEVE

Total # Posts: 48,651

Calculus
#1 correct ?[1,4] ?(1 + 1/4x) dx ?[1,2] ?(1+4y^2) dy where did you come up with [16,1]? The curve goes from (1,1) to (4,2) Note that ?(1+4y^2) is NOT (1 + 2y) ?(a^2+b^2) is not a+b !! #2. looks ok. For C, the radius is just x+2 For D, the radius is just 3-y
January 25, 2017

Math
use your standard conversion factors for gal/L and mi/km
January 25, 2017

Measurement
u = 10^-6 p = 10^-12 you surely have a list of prefixes - use them.
January 25, 2017

Algebra
you know that x = 3y-6 So, use that in the other equation: 20y + 35(3y-6) = 3795 20y + 105y - 210 = 3795 125y = 4005 y = 32.04 Now use that to find x. Odd, I expected an integer answer. Check for typos.
January 25, 2017

Algebra 1
just evaluate at x=5
January 25, 2017

Trigonometry with right triangles
you can always get a book on geometry and study it. I learned calculus on my own from my teacher's textbook. But I suggest you finish Algebra I before trying geometry or trig. It will give you a good foundation to work with.
January 25, 2017

Trigonometry with right triangles
what, you can't figure 90-25 ?
January 25, 2017

Trigonometry with right triangles
cos(x) = sin(90-x) That's what the co- in cosine means: sine of the complement.
January 25, 2017

Algebra 2
I get B. What did you do? Maybe we can figure what went wrong.
January 25, 2017

Calculus
sin = y/r cos = x/r sinx = 1/5 cosx = -?24/5 = -2?6/5 cosy = 1/8 siny = ?63/8 = 3?7/8 I'll do sin(x+y) and you can apply the formulas for the rest. sin(x+y) = sinx cosy + cosx siny = (1/5)(1/8)+(-2?6/5)(3?7/8) = 1/40 - 6?42/40 = (1-6?42)/40 makes sense, since x+y is in QIII
January 25, 2017

Algebra
If the walkway has width w, then 2(6+2w + 10+2w) = 60.8
January 25, 2017

maths
a = 31 1/4 = 125/4 ar^(n-1) = 2 r^(n-1) = 8/125 Now, 8/125 = (2/5)^3 Looks to me like r = 2/5 and n=4 and the sequence is thus 125/4, 25/2, 5, 2 I think you'll find it adds up to 203/4
January 25, 2017

Algebra
Draw a diagram. Set the center of the ellipse at (0,0). Then we have semi-axes a = 74 b = 48 x^2/74^2 + y^2/48^2 = 1 Now plug in y=10 and find x. The distance d is then d^2 = x^2 + 10^2
January 25, 2017

calculus
3xy^3+4xy=63 3y^3 + 9xy^2 y' + 4y + 4xy' = 0 y'(9xy^2+4x) = -(3y^3+4y) y' = -(3y^3+4y)/(9xy^2+4x) So, at (9,1) y' = -7/117 Now you have a point and a slope, so the line is y-1 = -7/117 (x-9) Refer to http://www.wolframalpha.com/input/?i=plot+3xy%5E3%2B4xy%...
January 25, 2017

Math 114
so, did you check? 3+9=12 so, ok.
January 25, 2017

MATH
well, 4 for each kg, so ...
January 25, 2017

math
72/4 = 18 So, multiply all the lengths by 18 to get 54+72+36 = 162
January 25, 2017

Math
-8+3 = -5
January 25, 2017

math
1/5 boys absent means 4/5 present 4/5 boys = 160 = 4*40 So, there are 5*40 = 200 boys 2/5 of the students are boys 200 = 2/5 * 500 So, there are 500 students in all. Now you can see how many are girls.
January 25, 2017

Trigonometry with right triangles
Since <DEF is 60° and DE = ?2, EF=?6. So, the area is (?2*?6)/2 = ?3 Rather than all this *line in between answer D* stuff, you could have just written ?3/?2
January 25, 2017

trigonometry
If the pedestrian is x meters from the short building, 10/x = tan20°10' the distance to the tall building is 40-x You don't seem to care how tall the other building is, but if the tall building has height h, then (h-10)/40 = tan15°20'
January 25, 2017

complex number help
?-16 = ?(16 cis ?) = ?16 cis ?/4 = 2(1/?2 + 1/?2 i) = ?2 + ?2 i That is the 1st root. There is an equivalent root in each quadrant. See http://www.wolframalpha.com/input/?i=x%5E4+%3D+-16 Work the 5th root the same way, using de Moivre's theorem.
January 25, 2017

maths
assuming that the wood purchased will be used efficiently, the volume of wood is the outside volume less the inside volume. Since there are parallel sides, the inner dimensions are 5 cm less than the outer. Thus, the volume of wood is (200-5)(120-5)(75-5) = 1569750 cm^3 = 1....
January 25, 2017

MATH
x^2 * x^2 = (x*x)*(x*x) = x*x*x*x = x^4 or, x^2 * x^2 = x^(2+2) = x^4 or, x^2 * x^2 = (x^2)^2 = x^(2*2) = x^4
January 25, 2017

Math
f(5/2) is the remainder when f(x) is divided by (x - 5/2) This site can help: http://calc101.com/webMathematica/long-divide.jsp
January 24, 2017

Math
see http://calc101.com/webMathematica/long-divide.jsp
January 24, 2017

Math
well, (8-5)^2 = 3^2 = 9 I assume you can take it from there ...
January 24, 2017

Calculus
a little synthetic division will show that f(x) has roots in (-2,-1) and (0,1).
January 24, 2017

Calculus
F'(-4) = lim(h->0) [((-4+h)^3 + (-4+h)^2) - ((-4)^3+(-4)^2)]/h = lim(h->0) [(h^3-11h^2+40h-48)-(-48)]/h = lim(h->0) (h^3-11h^2+40h)/h = lim(h->0) (h^2-11h+40) = 40
January 24, 2017

Calculus
secx = 2 or -2 or, cosx = 1/2 or -1/2 One root in each quadrant.
January 24, 2017

Calculus
The slope of the line is (30000-280000)/10 = -25000 So, V(t) = 280,000 - 25,000t
January 24, 2017

Math
A - 1/2a = P
January 24, 2017

Physics (9th)
sorry. 26.39/4 = 6.59 don't know how I got so far off. So, fix t and redo the calculation...
January 24, 2017

Physics (9th)
recall that the equation for distance is s = vt + a/2 t^2 95 km/hr = 26.39 m/s So, it will take 26.39/4 = 6 seconds of braking to stop. s = 95*7 - 2*6^2 = 593 meters to stop I guess she had good eyes, seeing an antelope at half a km away! Or, maybe she just hit it, or swerved ...
January 24, 2017

Algebra
p = 3b-6 20b+35p = 3790 Now just solve for b and p to see how many of each there are.
January 24, 2017

Math
correct
January 24, 2017

Math
oops 47+30 = 77 > 70
January 24, 2017

Math
well, 70-47 = 23 so, any number bigger than 23 will make the statement true 47+30 = 73 > 70 I have no idea what outlandish method they taught to solve the problem.
January 24, 2017

chem
impatient much? see your other post...
January 24, 2017

chem
29 moles of O2 --> 58 moles of H2O So, how many grams is that?
January 24, 2017

find the equation
review the point-slope form.
January 24, 2017

Standard Form
slope=0 so, the line is of the form y=k for some k.
January 24, 2017

trig
forget you algebra I?? subtract 2 from both sides ...
January 24, 2017

math
initial amount of $57 expense = 57 materials cost $7 for each necklace expense = 57 + 7x sales = 26x ...
January 24, 2017

math geometry
This might help. google can provide more help.
January 24, 2017

maths - Typo?
a = ar^3 + 13.5 ar^3 = ar^2 + 9 a(1-r^3) = 13.5 ar^2(r-1) = 9 Now divide both sides to get (1-r^3)/(r^3-r^2) = 13.5/9 2-2r^3 = 3r^3-3r^2 5r^3-3r^2-2 = 0 Hmmm. No real solutions.
January 24, 2017

Algebra
No, the solutions are the values of x which make x = 0 x+5 = 0 x+2 = 0 x = 0, -5, -2 x = 0 5x-1 = 0 x+4 = 0 x = 0, 1/5, -4
January 24, 2017

Calculus
Your pieces overlap. That is not the way to define a piecewise function. Looks like your inverse function will also be piecewise, no? Just take the inverse on each piece.
January 24, 2017

Anonyms
c = 2?r = 4? so, r=2 a = ?r^2 = 4? A square with area 4? has side ?(4?) = 2?? So, its perimeter is 4*2?? = 8?? Note that 8?? > 4?. A circle has minimum perimeter for a given area. Or, a circle has maximum area for a given perimeter.
January 24, 2017

math
Odd that you know it's a Bernoulli equation, yet seem to have no technique for solving such a well-known form. y = ±1/?(cx^2-6x^3) If you have not studied them, try here: http://tutorial.math.lamar.edu/Classes/DE/Bernoulli.aspx
January 24, 2017

Math geometry
x = 20+3(180-x)
January 24, 2017

Trig
you're welcome.
January 24, 2017

math
)&( ? !
January 24, 2017

Math - Algebra 1
16 cows * 4.5 cups/cow/day * 7days * 1bucket/250cups * $26.75/bucket = $53.93
January 24, 2017

Math - Algebra 1
for a given perimeter, a square has the largest area.
January 24, 2017

math
a square with diagonal d has side length s = d/?2 And the question should have been worded: The walkway is 24 meters long. To the nearest tenth of a meter, how long is the side of the playground?
January 24, 2017

Geometry probability
There are 5 blue out of 12 marbles. So, there is a 5/12 chance of drawing a blue marble. That means that in 4 draws, the chance of drawing a blue on the 1st draw only is 5/12 * 7/11 * 6/10 * 5/9 = 35/396 Now, add that to the chance of drawing a blue only on the 2nd, 3rd, of ...
January 24, 2017

Trig
3 - 1/5 tanx = 16/5 -1/5 tanx = 1/5 tanx = -1 Now recall that tanx is negative in QII and QIV
January 24, 2017

Maths
well, one revolution is ?d = 14? cm, so ...
January 24, 2017

help with trigonometry??
draw a diagram. review your basic trig functions. It should be clear that if the height is h, h/112 = tan62°
January 24, 2017

math
?2.8x+5.6 < 8.4 -2.8x < 2.8 x > -1
January 24, 2017

algebre
using the law of cosines, 12^2 = 10^2 + 8^2 + 2*10*8 cos? = 164+160cos? BD^2 = 10^2 + 8^2 - 2*8*10 cos? = 164 - 160(-20/160) = 184 BD = 13.56
January 24, 2017

Math grade 6, ratio
a = 3/7 b = 2/3 a = 2/3 * 3/7 = 2/7 c = 1 - 3/7 - 2/7 = 2/7 b/c = (2/7) / (2/7) = 1 c = 2/3 a = a-49 1/3 a = 49 a = 147 c = 2/3 a = 98
January 24, 2017

Grade 6, ratio
if there were x 50-cent coins and y dollar coins, then if 6 dollars were replaced with 12 halves, x/y = 3/4 (x-6)/(y+12) = 1/3 clearing the fractions, we have 4x = 3y 3(x-6) = y+12 4x-3y = 0 3x-y = 30 now we see that y=3x-30, so 4x-3(3x-30) = 0 4x-9x+90 = 0 5x = 90 x = 18 So, ...
January 24, 2017

Math
that is correct.
January 24, 2017

Math
they add to 90 degrees, so 4x+5x = 90 find x, and then the angles are 4x and 5x
January 24, 2017

Algebra
1 3/5 and 2 1/2 are both bigger than 1. how can each person eat more than the whole pizza? In any case, 1 3/5 + 2 1/2 = 1 6/10 + 2 5/10 = 3 11/10 = 4 1/10
January 24, 2017

Math
This just the sum of the first 12 terms of a geometric sequence with a = 3600 r = 1.01 So, 3600 * (1.01^12 - 1)/(1.01-1) = 45,657 Not quite sure how to get your answer.
January 24, 2017

Algebra
you know that x^a * x^b = x^(a+b) x^(1/2) * x^(1/2) = x^(1/2 + 1/2) = x^1 = x ?x * ?x = x (?x)^2 = (x^(1/2))^2 = x^(2 * 1/2) = x^1 = x
January 24, 2017

Math
they are equal due to the associative property of multiplication: (a*b)*c = a*(b*c)
January 24, 2017

Calc 2
Hmmm. Kind of murky. In any case, it's just the chain and product rules. y = ?x e^(x^2) (x^2+1)^10 Recall that if y=uvw then y' = u'vw + uv'w + uvw' So, that would give us y' = 1/(2?x) * e^(x^2) * (x^2+1)^10 + ?x * 2x e^x^2 * (x^2+1)^10 + ?x * e^x^2 * ...
January 24, 2017

Math
correct. It is shown.
January 23, 2017

Math
if you mean that the 2nd was sold for 20% more than the first, then if the first sold for x, we have x + 1.2x = 3000 If not, then I'm not sure what each gaining 20% on the other means...
January 23, 2017

Algebra
half as many workers, so twice as long.
January 23, 2017

Math
215lb * 1kg/2.2lb = 97.727kg 97.727kg * (4.8mg/day)/kg = 445.091 mg/day 445.091 mg/day * 11ml/16mg = 306ml/24hr = 76.5 ml/(6hr)
January 23, 2017

math
square roots that end with a decimal?? square roots are called radicals, but so are cube roots, etc. 3?2 = ?18 = ?18.000 not sure where you're going with this.
January 23, 2017

Precalulus
I am assuming the usual carelessness with parentheses, and getting -2/(-3x-7) - 3/(2x-1) = 3/2 -2*2(2x-1) - 3*2(-3x-7) = 3(-3x-7)(2x-1) 4-8x + 18x+42 = -18x^2-33x+21 18x^2+43x+25 = 0 (x+1)(18x+25) = 0 x = -1 or -25/18 Assuming a little less sloppiness, I'd read (-2/-3)x - ...
January 23, 2017

11th Grade Algebra 2
just review the techniques of long division. You can see all the details if you play around here: http://calc101.com/webMathematica/long-divide.jsp It's just like regular numeric long division, as long as you line up the powers of x the way you do columns of digits in big ...
January 23, 2017

Math
you can play around with these things here, and see all the details. http://calc101.com/webMathematica/long-divide.jsp
January 23, 2017

Math
96/6 = 16 All we know is that the base has an area of 16 ft^2. I'm sure you can some up with two factors of 16 which could be the length and width.
January 23, 2017

MATH @Damon @ms. Sue
f(x) = 2*3^x on [0,1] the average rate is (f(1)-f(0)))/(1-0) = (2*3^1 - 2*3^0)/1 = 6-2 = 4 on [2,3] the average rate is (f(3)-f(2))/(3-2) = (2*3^3 - 2*3^2)/1 = 54-18 = 36 the ratio of the rates is 36/4 = 9. The reason the rate increases is that exponentials grow ever faster. ...
January 23, 2017

Science
is it a windy day? is it raining? is the street sloping? curving?
January 23, 2017

Math
12:01 12:29 12:46 I'm sure you can come up with others. Heck, use a clock if you need to.
January 23, 2017

Calculus
#1. Using horizontal shells of thickness dy, r = y h = y^2 - (3y^2-2) = 2-2y^2 v = ?[0,1] 2?rh dy = 2??[0,1] y(2-2y^2) dy = ? You got r and h reversed, but the product was luckily the same. Unfortunately, you added instead of subtracting. Using discs of radius y and thickness ...
January 23, 2017

Math
well, 9 is 3/4 dozen, so it will cost 3/4 of 20, or 15 Or, since the unit cost as the ratio of money:bananas is constant, x/9 = 20/12
January 23, 2017

HELP PLEASE
the C balances as written, since there is one on each side. That leaves you with CH4 + ?O2 > CO2 + ?H2O you have 4H on the left, so you will need 2H2O on the right. That gives CH4 + ?O2 > CO2 + 2H2O That balances the C and H, so now you need 4O on the left, which is 2O2 ...
January 23, 2017

Math
correct, so now you can find the breadth, b.
January 23, 2017

Math
2(b + 2b-8) = 56
January 23, 2017

algebra
an equation has no coordinates. If you want the coordinates of the two lines' intersection, then just solve for x and y. The first equation tells you that y = 2x+11 so use that in the 2nd equation and you have x+4(2x+11) = 17 x+8x+44 = 17 9x = -27 x = -3 Now, y = 2x+11 = 2...
January 23, 2017

algebra
sorry. (a) we don't have the test in question (or even the class!) (b) we don't help students cheat we will help you learn how to solve the problems, though, if it's not already too late ...
January 23, 2017

Math
If those are logs to the same base, then 5(x-2)*8(x-4) = 6(x-1) x = (123+?2089)/40 If those are logs to different bases (5,8,6), it takes some more work. Changing all to natural logs, we have Log5(x-2) + log8(x-4)= log6(x-1) ln(x-2)/ln5 + ln(x-4)/ln8 = ln(x-1)/ln6 ln8*ln6*ln(x...
January 23, 2017

Pre-Calculus
the water surface has a constant area of 800 in^2. So, every inch of water adds a volume of 800 in^3. So, after t minutes, the tank holds v(t) = 7*800 + 800t in^3 You should probably restrict the domain of t so that the tank does not overflow.
January 23, 2017

Study School (Math)
t+u = 9 10t+u+9 = 10u+t Now just find t and u, then answer the question.
January 23, 2017

college algebra
try writing it without the words. This is a math problem, not an English essay ... -4/(2x+3) + 1/(x-1) = 1/((2x+3)(x-1)) -4(x-1) + 1(2x+3) = 1 -4x+4 + 2x+3 = 1 -2x+7 = 1 2x = 6 x = 3
January 23, 2017

college algebra
Put the words into math. You are told that: s+g = 10000 g = s-3000 Now just solve for s and g.
January 23, 2017

Math
(48ft*48ft) * (1can/192ft^2) = (2304ft^2) * (1can/192ft^2) = 12 cans
January 23, 2017

maths
This one is long, but not overly complicated. I expect that u=x^2 is a good substitution to start with. Then I expect a trig or hyperbolic trig substitution will come in handy. I suggest you enter your integrand at this URL and it will show all the steps involved. http://www....
January 23, 2017

Math
no, since the discriminant (b^2-4ac) is negative. The roots are complex.
January 22, 2017

math question
distance=speed*time So, if it flew at 800km/hr for x hours, then it flew at some unknown speed s for 2x hours: 800x + s*2x = 700*3x 800+2s = 2100 2s = 1300 s = 650
January 22, 2017

Precalculus
oops. the cubes factor as (x + (x+1))(x^2-x(x+1)+(x+1)^2)
January 22, 2017

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