Saturday

December 10, 2016
Total # Posts: 47,054

**G.p.**

a = 1 r = 1/2 S12 = (1 - 1/2^12)/(1 - 1/2)

*December 8, 2016*

**G.p.**

b-a = c-b 1/a^2 - 1/b^2 = 1/b^2 - 1/c^2

*December 8, 2016*

**Math**

well, add 'em up: 2 4/8 3 3/8 1 2/8 ------- 6 9/8 = 7 1/8

*December 7, 2016*

**math**

(450-45)/450 = ? Or, you can reason that 45 is 10% of 450 that were used, so ...

*December 7, 2016*

**Trigonometry**

24.91 @ S36°W

*December 7, 2016*

**MATH, please help**

they are in proportion because 8*9 = 6*12 In a proportion a/b = c/d ad = bc

*December 7, 2016*

**Math**

12% is about 1/8 so, you need about 8 times the amount.

*December 7, 2016*

**Math**

There must be a typo. It is 2x^3+5x^2+x-7 So, (C) could be right, if it has the typo.

*December 7, 2016*

**Math**

the slope is -A/B So, of course, B cannot be zero. That gives the equation Ax=C which is a vertical line, so the slope is undefined.

*December 7, 2016*

**Math**

right.

*December 7, 2016*

**Check Answer!!**

That is right.

*December 7, 2016*

**Math**

linear: constant difference quadratic: constant 2nd differences exponential: constant ratio over equal intervals

*December 7, 2016*

**Check Answer!!**

4600(1+.025/4)^(4*8) = 5614.96 what formula did you use?

*December 7, 2016*

**precalculus**

well, you know it will be in QIV, so 270 < ? < 360 arctan(7/3) = 66.8014° But you want arctan(-7/3) = -66.8014°, in QIV. So, add 360 to that to get 293.19° Hmmm. Not one of the choices. However, arctan(-3/7) = 337° Looks like there was a typo in the problem.

*December 7, 2016*

**precalculus**

tan?/sec? = sin? Now do you have an idea?

*December 7, 2016*

**Algebra**

the 2nd is just the first, shifted down 9 That is, subtracting 9 from the y-values moves the graph downwards. Try it.

*December 7, 2016*

**Geometry**

yes.

*December 7, 2016*

**Geometry**

D is the biggest angle, so the opposite side (EF) is the longest side. Now do the others similarly.

*December 7, 2016*

**Math**

I can find no solutions.

*December 7, 2016*

**Geometry**

Draw a diagram. Note that AE is divided into two pairs of equal lengths. BD contains one of each pair. So, BD is half the length of AE. 2(3x+5) = 4x+20 x = 5

*December 7, 2016*

**algebra 1**

since the lines have different slopes, they intersect. Now just use the value of y from eq #2 and substitute it into eq #1 to get the value of x. Then you can get y.

*December 7, 2016*

**Math**

look for SSS in the lengths of the sides of the triangles formed.

*December 7, 2016*

**precalculus**

I doubt I can explain it any more clearly than (a) your text (b) the many discussions provided using google.

*December 7, 2016*

**math**

7(a+6d) = 11(a+10d) 7a+42d = 11a+110d 4a+68d = 0 a+17d = 0 T18 = a+17d = 0

*December 7, 2016*

**analytic geometry**

x and y have increased by 2. Extending the line 3 times more will increase each by 6. So, the desired point is (9,9)

*December 7, 2016*

**duet**

the terms are a, a+d, a+2d, a+3d so you want to show that a^2 - (a+3d)^2 = 3((a+d)^2 - (a+2d)^2) Now just verify that by expanding both sides.

*December 7, 2016*

**math(A.P)**

The sum of the 1st n odd numbers is n^2. So, n^2 > 5000

*December 7, 2016*

**Maths**

(25-2x)(30-2x) = 300

*December 7, 2016*

**maths**

Let AB=AC = x, and the base BC = 2y Then you have 2x+2y = 64 y^2 + 24^2 = x^2 (32-x)^2 + 24^2 = x^2 x = 25 You might have guessed this right off, since one of the basic right triangles with integer sides is 7-24-25 Of course, a 3-4-5 triangle scaled up by 6 would be 18-24-40 ...

*December 7, 2016*

**math**

just use the formulas you know, and write down the facts as given: S25 = 25/2 (2a+24d) = 200 S3 = 3/2 (2a+2d) = 4.2 Solve those two equations, and you get a = 4/5 d = 3/5 "larger" indicates only two items. I assume you mean the "largest" term, which is T25...

*December 7, 2016*

**Geometric progression**

1+2^1+2^2+...+2^n = 2^(n+1)-1 So, the sequence becomes 2^1-1 + 2^2-1 + 2^3-1 + ... + 2^n-1 = 2^1 + 2^2 + ... + 2^n - n = 2^(n+1)-1 - n-1 = 2^(n+1) - (n+2) check (n=5): 1+3+7+15+31 = 2^6-7 = 57

*December 7, 2016*

**G.p.**

same old same old, with a = 1 r = -1/2

*December 7, 2016*

**G.p.**

Sn = a(1-r^n)/(1-r) Just use your formula.

*December 7, 2016*

**math**

just plug and chug: a+8d = 0 25/2 (2a+24d) = 50 8d = -a, so 25/2 (2a-3a) = 50 a = -4

*December 7, 2016*

**math**

of course not. multiplying miles by miles gives you area: miles^2 Keep track of the units and all becomes clear: 1 km = 0.62 mi that means that 1km/0.62mi = 1 Now, you can always multiply by 1 and not change things. So, since you want to convert miles to km, 26mi * 1km/0.62mi...

*December 7, 2016*

**G.p.**

when x/(x-2) = (x+3)/x

*December 7, 2016*

**math**

the one rising from 270 with a slope of 80

*December 6, 2016*

**physics**

correct.

*December 6, 2016*

**Math**

so you want the left limit (as x->2 from below) Now, recall the definition of |u| |u| = u if u >= 0 |u| = -u if u < 0 When x < 2, x-2 < 0, so |x-2| = 2-x So, the limit is (2-x)/(x-2) -> -1 You can see this on the graph at http://www.wolframalpha.com/input/?i...

*December 6, 2016*

**Math**

(?(2x+3)-?(3x))/(x^2-3x) If you have l'Hospital's Rule as a tool, then you know that the limit is the same as (1/?(2x+3) - 3/(2?(3x)) / (2x-3) = (1/3 - 3/6)/3 = -1/18

*December 6, 2016*

**Math**

g(k) = -k^2 + 4k + 1 I suspect there is more to this question...

*December 6, 2016*

**maths**

both numbers are multiples of 7. 77 = 7*11, so you want two numbers which sum to 11, and have no factors in common. That would be 1,10: 7+70 = 77 2,9: 14+63 = 77 ...

*December 6, 2016*

**Math liberal arts 2**

yes! m is the slope. That's why y=mx+b is called the "slope"-intercept form of the line.

*December 6, 2016*

**Algebra**

what's the trouble? Each term, starting with the 3rd, is the sum of the two previous terms. Since the first two terms are 9,9 the sequence continues with 9+9 = 18 9+18 = 27 18+27 = 45 ... You might try writing the sequence as a_(n+1) = a_n + a_(n-1) saves using all those ...

*December 6, 2016*

**Algebra**

parent: y = ?x shift left 7.3 gives y = ?(x+7.3) stretch by 9 gives y = 9?(x+7.3) reflection changes the sign of the y-values, so y = -9?(x+7.3) square root is a particular function. cube root is not "^3 squareroot" Try saying cube root 4th root 5th root etc. instead...

*December 6, 2016*

**Algebra**

vertical asymptotes: 1/((x+2)(x-7)) root at x = -5: (x+5)/((x+2)(x-7)) horizontal asymptote. we need the degree to be equal, so try 7x(x+5) -------------- 2(x+2)(x-7) The problem here is that now we have another x-intercept at (0,0) So, let's work with 7(x+5)^2...

*December 6, 2016*

**Algebra**

vertex at t = -b/2a = 570/32 = 285/16

*December 6, 2016*

**Fraction Test Question**

4x8 = 8x4 4/4 = 8/8 4x8/8 = 4

*December 6, 2016*

**math - bogus**

ever actually read what you posted?

*December 6, 2016*

**algebra**

so, draw the graphs, or make a table. No problema, right?

*December 6, 2016*

**Algebra 2**

Think of moving the y-axis 4 units to the right. All the x distances would be 4 less than they are now. So, y = (x-4)^2 is just the parabola y=x^2, moved 4 units to the right! replacing x by (x-h) moves the graph h units to the right. you can see this here: http://www....

*December 6, 2016*

**Pre-Calculus**

clearly you need to review this topic e < 1 ellipse e = 1 parabola e > 1 hyperbola

*December 6, 2016*

**Calculus**

try this site: http://www.wolframalpha.com/input/?i=plot+r+%3D+cos+5%CE%98+%2B+n+cos+%CE%98,+0+%E2%89%A4+%CE%98+%E2%89%A4+%CF%80,+n%3D1

*December 6, 2016*

**Trigonometry**

3 rpm = 6? radians/min 2?*25*3 = 150? ft/min

*December 6, 2016*

**Math**

Not quite. ?(75p^3q^2) = 5?3 pq?p ?(p^5q^4) = p^2q^2 ?p divide and you end up with (5?3)/(pq) Hmm. I guess you could have meant 5?(3/(p^2q^2)) but that simplifies to my result above

*December 6, 2016*

**Cal 3**

critical points are where they are both zero. So, you need x^3+y^3-15x^2-6xy+18y^2+39x+138y 3x^2-30x-6y+39 = 0 3y^2-6x+36y+138 = 0 http://www.wolframalpha.com/input/?i=solve+3x%5E2-30x-6y%2B39+%3D+0,+3y%5E2-6x%2B36y%2B138+%3D+0 http://www.wolframalpha.com/input/?i=minima+x%5E3...

*December 6, 2016*

**Algebra II**

real: 4,2,0 Using Descartes' Rule of Signs, positive: 2 max negative: 2 max complex: 4,2,0 how come (a),(b),(c) are all the same?

*December 6, 2016*

**Trigonometry**

cot(x) has period pi cot(x/3) has period 3pi Now add in the rest.

*December 6, 2016*

**Applied calculus**

pi, not pie or pai or ... try typing your functions in here. http://www.wolframalpha.com/input/?i=plot+x%3D2cos(2t),+y%3D2sin(3t),+0%3C%3Dt%3C%3D2pi rather than expressing them as vector components, use parametric equations.

*December 6, 2016*

**Algebra**

keep track of the amount of antifreeze in each part, and the whole: .25x + .60*4 = .45(x+4)

*December 6, 2016*

**CALC**

google is your friend. Many of these problems have been solved before, or ones like them. www.math.umn.edu/~emanlove/2263sum11/HW%2034.pdf

*December 6, 2016*

**precalculus**

well, geez -- just look at the equations. Surely you can notice the +/- signs, axis lengths, etc.

*December 6, 2016*

**Calc**

dy/du = sec^2u du/dv = 1 + 1/v^2 dv/dx = 1/x dy/dx = dy/du * du/dv * dv/dx now just crank it out. It's just algebra from here.

*December 6, 2016*

**math**

is (2,1) supposed to end up at (-1,4)? If so, why the intermediate point? The final translation is just (x,y) -> (x-3,y+3)

*December 6, 2016*

**Science. Answer Check**

false. In a series circuit, one failure causes the whole chain to stop. Parallel means that the current flows through each light "in parallel" with the others -- the lights each get their own current. Better look at a circuit diagram again to refresh your memory.

*December 6, 2016*

**math**

Hmmm. The problem says 9 people. How do you justify your answer?

*December 6, 2016*

**Algebra**

6200 * 1.08^t = 8750 * 1.06^t (1.08/1.06)^t = 8750/6200 ...

*December 6, 2016*

**elimination**

rearrange things to a standard format: x - 2y = -7 8x + 5y = 7 multiply #1 by 8: 8x - 16y = -56 8x + 5y = 7 Now just subtract, and the x's are eliminated...

*December 6, 2016*

**math**

Nope. -5(8) = -40 Now subtract 4 Your answer is -4 -5(w-8)

*December 6, 2016*

**math**

a=7 d=3 ...

*December 6, 2016*

**Math**

If the distance is x, then we have for the area a = 15*4 = 8x

*December 6, 2016*

**Maths**

looks like 4.5 for depth, -4.5 for height

*December 6, 2016*

**math**

2?rh = 1760 ?r^2h = 12320 square the area equation, and now you have 4?^2 r^2 h^2 = 1760^2 ?r^2 h = 12320 Divide and you have 4?h = 1760^2/12320 ...

*December 6, 2016*

**Math**

Your equation just satisfies y varies directly as x. What about the rest? y = ax + b/x + c Now use the points to get 3 equations in a,b,c and solve them.

*December 6, 2016*

**Calc**

dy/dx = dy/dt / dx/dt = (3/(2?(3t+1))) / (3t^2-1) at x=1, that is (3/(2*2))/(2) = 3/8

*December 6, 2016*

**Calc**

plug in lnx for x and then use the chain rule. f(lnx) = 6(lnx)^3 - 4lnx

*December 6, 2016*

**Calculus**

The question is incomplete: smallest n for what? You can easily verify that y^(2) = -y y^(4) = y and the odd orders are plus/minus cosine.

*December 6, 2016*

**Maths**

see related questions below

*December 6, 2016*

**Math**

If the numerator is even and differs by 3 from the denominator, then the denominator is odd. (Thus, the prime 2 is ruled out.) At that point, saying that their product is even is redundant. odd primes are 3,5,7,11,13,... So, the fraction could be 2/5, 4/7, 14/11, ...

*December 6, 2016*

**G.p.**

again? ar^6 = 1/9 ar = 27 divide, and you have r^5 = 1/3^5 r = 1/3 So, a=81

*December 6, 2016*

**maths**

2*5 = 10 so its fractions terminate. Try using 3 and see what happens.

*December 6, 2016*

**Meth**

fix the typo. Then maybe we can pick an answer.

*December 6, 2016*

**harmonic progression**

since the reciprocals are in AP, yes, it is an HP.

*December 6, 2016*

**Algebra**

well just plug in t=6 into your somewhat awkward formula.

*December 6, 2016*

**G.p.**

is that 2^(2-b) or 2^2 - b?

*December 6, 2016*

**math**

x + x+2 = x+4 + 16

*December 6, 2016*

**g.p.**

ar^3/ar^11 = 1/r^8 = 1/2^8 so, r = 2 I expect you can take it from there...

*December 6, 2016*

**Calculus**

I'd say no. It's just an exponential function. No way any logs can creep in there.

*December 6, 2016*

**Calculus**

well, geez - did you try it to check? f = e^(1-x) = e*e^-x f' = e*(-1)e^-x = -f

*December 6, 2016*

**Calculus**

Just using the product, quotient, and chain rules, I'd say (u'v + uv')(w) - uvw' --------------------------- w^2

*December 6, 2016*

**Calculus**

y = x + 4/x has a max at x = -2

*December 5, 2016*

**Calc**

v = x(6x)*y y = V/(6x^2) A = x*6x + 2xy + 2*6xy = 6x^2 + 14xy = 6x^2 + 14x(V/6x^2) = 6x^2 + 7V/(3x) Now just find where dA/dx = 0.

*December 5, 2016*

**Alegbra**

you have basically a = bR^3 R^3 = a/b = 15000/(4pi/3) = 45000/4pi = 11250/pi R = ?(11250/pi)

*December 5, 2016*

**Pre Calculus**

just solve for t when h(t) = 0.

*December 5, 2016*

**Math**

A better question might be how did you get yours? Did you draw a diagram? since sin(30) = 1/2, the pole is 15/2 meters tall. A 45-45-90 triangle has equal legs, so base of the 2nd wire is 15/2 meters from the pole. I'll leave the rest to you. The Pythagorean Theorem should...

*December 5, 2016*

**Math**

That's not what I get. I get (15/2)(?3-1) How did you get your answer (which is not exact, by the way)?

*December 5, 2016*

**Algebra**

the maximum profit is at the vertex of the parabola. As you know, the vertex of the parabola ax^2+bx+c is at x = -b/2a y = (b^2-4ac)/4a So, for -10x^2+100x-210 the vertex is at (5,40) Since x=5, the price is 10-x = 5 as well.

*December 5, 2016*

**math**

If their numbers are x,y,z, then we know x/y = 2/7 x/z = 2/3 z = y-8 x+y+z = 24

*December 5, 2016*

**Science**

Recall that F = ma Now just use your numbers.

*December 5, 2016*