Monday

February 27, 2017
Total # Posts: 48,822

**pre Calc**

clearly the slope is -3.5 Now think f=mt+b

*January 4, 2017*

**Number Theory**

4x+7 = 2(mod 15) 4x = -5(mod 15) 4x = 10(mod 15) so, what can x be so that 4x = 5k+10 for some k?

*January 4, 2017*

**precalc**

you know that cos(u) might either decrease or increase, depending on u. surely t/52 increases when t does. !!

*January 4, 2017*

**Math**

x = -2 is a vertical line. So, what is the horizontal line through the point? x = -5 is parallel to x = -2, not perpendicular.

*January 4, 2017*

**Math**

F = ma just add up the vectors, after dividing by the mass.

*January 4, 2017*

**Math**

surely you can graph the lines y = 2/3 x y = -2 y = -3x+1 then just take the pieces you need.

*January 4, 2017*

**Pre Calc**

the slopes must be the same, so (8-1)/(2-a) = (1-6)/(a+2-12) a = 30

*January 4, 2017*

**profit&loss mathematics**

come on. B paid 20% of A's cost: 1.20A C paid what A did: B/1.20 = 08.3333B So, B lost 16.666 % maybe my math looks as funny to you as your texting does to me...

*January 4, 2017*

**profit&loss mathematics**

B = 1.20A C = A = B/1.20 = (5/6)B so, that is ...

*January 4, 2017*

**Maths**

?x^2 h = 800 h = 800/(?x^2) The area is two circles plus a curved cylinder, so a = 2?x^2 + 2?xh the result follows, so just find x such that da/dx = 0

*January 4, 2017*

**mathematics**

sorry - a=20 ! :-(

*January 4, 2017*

**mathematics**

you must be studying geometric sequences, so just note that this is the sum of the sequence with a = 12 r = 3/5 Now just use your formula for the infinite sum: s = a/(1-r)

*January 4, 2017*

**am I right ? or no?**

you are correct that b^x is growth if b>1 and decay if b<1

*January 4, 2017*

**Maths**

convert the area to m^2 area = length*width, so divide by the width to get the length

*January 4, 2017*

**Maths**

0.5ha * (10000m^2/ha) / 12.5m = 400m

*January 4, 2017*

**algebra - duh @Reiny**

It usually helps to read the problem carefully. Nice work, Reiny

*January 4, 2017*

**algebra**

x+y <= 9x-5y 6y <= 8x 3y <= 4x You might also want to consider x+y <= |9x-5y|

*January 4, 2017*

**Maths**

n = d-7 (n+2)/(d+9) = n/d (d-7+2)/(d+9) = (d-7)/d d(d-5) = (d-7)(d+9) d^2-5d = d^2+2d-63 7d = 63 d=9 check: original fraction: 2/9 modified fraction: 4/18 = 2/9

*January 4, 2017*

**Maths**

if you have a unix system, you can use the bc calculator for arbitrary precision, as well.

*January 4, 2017*

**Math**

1/4 of 2 cups is ??

*January 4, 2017*

**math**

((3200/1.60)/4)^2 * 1.20/100 = 3000

*January 4, 2017*

**Math**

there are 4 choices for each digit, so 4^4 total ways. 3/4 of them start with a number less than 7, right?

*January 4, 2017*

**Math;);)**

the two points lie on the unit circle, clearly 54-19 degrees apart. The angle is 35°. or, use the distance formula to find the vector u-v. Then use the law of cosines to find the included angle.

*January 4, 2017*

**math**

Just plug in n=5: a5 = 6*5-4 = ?

*January 3, 2017*

**Math**

well, the equations is (x-(2-3i))(x-(2+3i)) = 0 ((x-2)+3i)((x-2)-3i) = 0 (x-2)^2 + 3^2 = 0 x^2-4x+4 + 9 = 0 x^2-4x+13 = 0 a+b = -4+13 = 9

*January 3, 2017*

**Math**

try using letters like a,b,c instead of the special characters that are getting mangled.

*January 3, 2017*

**maths**

if x<0>=0 then 4/(x<0>)^2 is undefined. I'll assume that x<n+1> = 4/(x<n>^2+5) If so, then x<0> = 0 x<1> = 4/(0^2+5) = 4/5 = 0.8 x<2> = 4/(0.8^2+5) = 4/5.64 = 0.7092 ... The actual root ? 0.72408 If I got the formula wrong, then ...

*January 3, 2017*

**maths**

areas grow as the square of the linear factor. So the areas are A:B = (8:10)^2 = 64/100 = 16/25 A/160 = 16/25 A = 16*160/25 = 102.4 cm^2

*January 3, 2017*

**math**

tan(x) = h/d = 4d/d = 4 x = arctan(4) = 76° for part b, h decreases, because x decreases.

*January 3, 2017*

**math**

3^-n = 0.2 3^n = 1/0.2 = 5 (3^4)^n = (3^n)^4 = 5^4 = 625

*January 3, 2017*

**Maths**

V = 4/3 ? r^3 A = 4? r^2 = 3V/r = ?(36?V^2) Now just plug in your numbers.

*January 3, 2017*

**Algerbra**

He will need (253.5/6)^(3/2) * 2 = 549.25 kg of clay So, he will need 55 10kg bags

*January 3, 2017*

**Surfaces of cones**

?r?(r^2+h^2) = 2160? (12x)?(144x^2+256x^2) = 2160 (12x)(20x) = 2160 x^2 = 9 x = 3 so, the volume is ?/3 r^2h = (?/3) (24*3)^2 (16*3) = 82944? V = 82944 cm^3

*January 3, 2017*

**Maths**

just expand the left side. It will be the same as the right side. One way to start would be (3x-1)(x+5)(4x-3) = 3x(x+5)(4x-3)-(x+5)(4x-3) Now, (x+5)(4x-3)=4x^2+17x-15 so you can proceed with = 3x(4x^2+17x-15)-(4x^2+17x-15) = ...

*January 3, 2017*

**Math**

sorry - only one equation.

*January 3, 2017*

**Math**

useless problem. 6 apples - 2 oranges =

*January 3, 2017*

**Math**

Q = 10-P so, P^2-Q^2 = 40 P^2-(10-P)^2 = 40 20P-100 = 40 20P = 140 P = 7 So, Q = 3 check: 7^2-3^2 = 49-9 = 40

*January 3, 2017*

**algebra(difference of two squares)**

Your answer is clearly incorrect, since you want integers. The problem is that odd numbers differ by 2, so (n+2)^2-n^2 = 336 now it should work better.

*January 3, 2017*

**Math**

T = k?L using L'=1.4L instead, we have T' =k?L' = k?(1.4L) = k?L ?1.4 = T?1.4

*January 3, 2017*

**trigonomentry hope steve or damon reiny can help**

Lat's just use u and v for ease of typing x = cosu + i sinu y = cosv + i sinv (x-y)/(x+y) = (cosu-cosv) + (sinu-sinv)i ------------------------------- (cosu+cosy) + (sinu+siny)i Now multiply top&bottom by the conjugate of the denominator, collect terms, and recall that tan...

*January 3, 2017*

**Maths**

AB = 2x = 1.7 CD = 3x = 2.55 BD/CD = tan52° BD = 2.55 tan52° = 3.264

*January 3, 2017*

**math**

1800/1350 * 3

*January 3, 2017*

**MATH**

3:9

*January 3, 2017*

**Math**

If n were nabbed, then letting j = the jaywalkers, we have n/4 = j Now go on to the next sentence...

*January 3, 2017*

**Math**

well, check the differences: 1-1=0 4-3=1 9-7=2 16-13=3 25-21=4 So, how does that relate to n?

*January 3, 2017*

**Mathmatics**

If the two numbers are n and n+1, then we have (n+1)^2 - n^2 = n^2+2n+1-n^2 = 2n+1 = n + n+1

*January 3, 2017*

**Math (please check my answer!!)**

correct

*January 3, 2017*

**math**

looks good to me. S=131 L=452 = 2*131+190 = 131+321

*January 3, 2017*

**Math**

I suspect it was 30 by 20 to start with.

*January 3, 2017*

**Maths**

but yes, you are in fact correct.

*January 3, 2017*

**Maths**

huh? a,b,c are the coefficients in the equation, as usual!

*January 3, 2017*

**Math**

Reiny's answer is correct, according to (1 + x/(1-x) / (1 - x/(1-x) ) The domain is all reals except x = 1/2 or 1 Even though the domain of 1/(1-2x) only excludes x = 1/2, we also need to exclude x=1 since f(1) and g(1) are undefined, so f(g(1)) cannot be defined either.

*January 3, 2017*

**math coordinate geometry**

fix what's missing and maybe we'll give it a shot.

*January 3, 2017*

**maths**

tanx+tan2x+?3tanx tan2x=?3 tanx+tan2x = ?3 - ?3tanxtan2x tanx+tan2x = ?3(1-tanx tan2x) (tanx+tan2x)/(1 - tanx tan2x) = ?3 tan3x = ?3 ...

*January 2, 2017*

**Math**

(x+1)^3 = ?(x^2)

*January 2, 2017*

**math**

yes

*January 2, 2017*

**science**

Looks more like B and C to me. It takes force to turn the turbines. The weight of the water is force. The height it falls increases the momentum of the water, which is transferred to the turbines. Water which is not flowing (falling) exerts no force to turn the turbines.

*January 2, 2017*

**Math**

100000*(56/100)^(t/(2010-1990)) massaged as needed

*January 2, 2017*

**trigonomentry ps**

oh, yes. x=3?/2 also works.

*January 2, 2017*

**trigonomentry**

you can rewrite it as sinx + cosx + cos^2(2x) = 0 clearly x= 3?/4, ?, 7?/4 are some solutions. To find them all will take some doing. working with our equation, -sinx = cos^2(2x) + cosx square both sides to get sin^2(x) = cos^4(2x) - 2cos^2(2x)cos(x) + cos^2(x) 1-cos^2(x) = (...

*January 2, 2017*

**Algebra**

(x+1)^3 = ?(x^2)

*January 2, 2017*

**Math**

50+10m

*January 2, 2017*

**algebra**

2x-2 < -12 2x < -10 x < -5 2x+3 > 7 2x > 4 x > 2 So, x < -5 or x > 2 Work the other in like wise. Just clear the fractions first to make things easier.

*January 2, 2017*

**integral calculus**

see Mycah's post below

*January 2, 2017*

**business maths**

a worthy goal, to be sure.

*January 2, 2017*

**SAT MATH**

Line m has slope -3/8. So, using the point-slope form, y-(r-2) = -3/8 (x-r) or, 3x+8y = 11r-16 Now solve that along with 8x-3y=n and set the intersection to be (r,r-2). Then solve for r in terms of n.

*January 2, 2017*

**integral calculus**

Hmmm. I get x/2 - sin(2x)/4

*January 2, 2017*

**Add math**

?((x-4)^2+(y-8)^2) = 2?((x+2)^2+(y-3)^2) square both sides and collect terms. It will be a circle. http://www.wolframalpha.com/input/?i=circle+((x-4)%5E2%2B(y-8)%5E2)+%3D+4((x%2B2)%5E2%2B(y-3)%5E2)

*January 2, 2017*

**Add math**

1+y+1+2y+2+13+16 = 6*9 Find y, then get ?^2 as usual.

*January 2, 2017*

**Add math**

max area when square. So, 12x = 4-x

*January 2, 2017*

**Add Math(rate of change)**

v = ?r^2h dv/dt = 2?rh dr/dt + ?r^2 dh/dt Now just plug in your numbers to get dr/dt Note that since h=2r, dh/dt = 2 dr/dt Or, since h=2r, v = ?r^2h = 2?r^3 dv/dt = 6?r^2 dr/dt

*January 2, 2017*

**Analytic Geometry**

the slope is 1. So, the line is y = x+1

*January 1, 2017*

**mathematics**

a + a+d = 4 a+9d = 19 a+4d + a+5d = ?

*January 1, 2017*

**calculus-add**

see your earlier post for #1 For #2, review your techniques for 1st order linear ODEs, and see whether you can get the solution given here: http://www.wolframalpha.com/input/?i=(x-2)+dy%2Fdx+%3D+1-3y(x-1)%2F(x%2B1) Solve the homogeneous equation using partial fractions, and ...

*January 1, 2017*

**calculus**

huh? simple separation of variables. (2y-1) dy = (3x^2+1) dx y^2-y = x^3+x + C Using your point (1,2), find C: 4-2 = 1+1+C C = 0 y^2-y = x^3+x y = (1±?(4x^3+4x+1))/2

*January 1, 2017*

**Analytic Geometry**

C is the center, so 4 = (-1+x)/2 6 = (y+8)/2 ...

*January 1, 2017*

**Analytic Geometry**

Draw your line segment with the labeled points. It should be clear that LM=10 Now you can plug in the lengths required to evaluate the expression.

*January 1, 2017*

**shaekh**

a ba - a bb

*December 31, 2016*

**Algebra**

z/z = 1 so, multiply by that.

*December 31, 2016*

**Algebra**

the elevation is already given as an integer...

*December 31, 2016*

**Algebra**

commutative means they can be written in reverse order. So, ...

*December 31, 2016*

**algerbra**

you have the numbers. Just use them.

*December 31, 2016*

**Algebra**

we usually think of win as positive lose as negative

*December 31, 2016*

**integral calculus**

coth * sinh = cosh so your integral is just 1/cosh^2(2x) dx = sech^2(2x) dx That's just a standard form (almost).

*December 31, 2016*

**Algebra**

google is your friend: http://m.nextgurukul.in/nganswers/ask-question/answer/The-ratio-of-the-sum-of-n-terms-of-two-APs-is-7n14n27/Arithmetic-Progressions/21214.htm

*December 31, 2016*

**Surds**

?(2+?3) = ?((4+2?3)/2) = ?((1+2?3+3)/2) = ?((1+?3)^2/2) ...

*December 31, 2016*

**Math**

using similar triangles, the tree is 24/4 = 6 times as high as Palmer's eye.

*December 30, 2016*

**Math**

well, y = 35.00 + 1.50 x, so ...

*December 30, 2016*

**Math**

just use the [power rule to find the derivative of each term: d/dx x^n = n*x^(n-1) As for finding the roots, derivatives don't help much with that. But, digging back into your Algebra I skill set, note that f(x) = -x^2(x+1) + 16(x+1) = (16-x^2)(x+1) ...

*December 30, 2016*

**math**

Using brute force, since a = (-1+?23 i)/6 27a^4 = (49+11?23 i)/6 and so does 11a+10

*December 30, 2016*

**math**

see related questions below

*December 30, 2016*

**math**

the same as the difference between -2 and 2 or -10 and 10 since -(x-3) = 3-x

*December 30, 2016*

**Maths**

20*10 - 16*6 = ?

*December 30, 2016*

**calculus help**

dm/dx = -w(l-x) dm = -w(l-x) dx m = w(l-x)^2/2 + C you cannot just say that M = wl^2/2 It has to be for some value of x. I presume you meant to say that M(0) = wl^2/2 in which case C=0

*December 30, 2016*

**maths**

see whether this gives you some ideas: http://softwareengineering.stackexchange.com/questions/158315/what-does-value-propagation-mean However, elimination might be more useful here. You can manipulate the equations so that this is easy. 3x+2y=4 2x-3y=7 9x+6y = 12 4x-6y = 14 ...

*December 30, 2016*

**Math**

(1200/.90)*1.10

*December 30, 2016*

**Geometry**

since perimeter is a linear quantity, it scales the same as the length: the scale factor is 2.

*December 30, 2016*

**maths and science**

since 4/5 is submerged, its density is 4/5 that of water.

*December 29, 2016*

**Math Trigonometry**

If the point directly below the plane is P, and the two towns are W and E, then their separation is 8cot34° + 8cot49°

*December 29, 2016*