Saturday

February 25, 2017
Total # Posts: 48,792

**Algebra 2**

geez, what's with all the words? f(x) = x^2 + 3x + 6 g(x) = (x-3)/2 g(1) = (1-3)/2 = -1 f(-1) = (-1)^2+3(-1)+6 = 1-3+6 = 4 or, f(g(x)) = g^2+3g+6 = ((x-3)/2)^2 + 3(x-3)/2 + 6 = (x^2+15)/4 f(g(-1)) = ((-1)^2+15)/4 = 16/4 = 4

*February 25, 2017*

**math**

well, is f(1)=19? yes. So, f-1(19) = 1

*February 25, 2017*

**math**

sorry - not much specific information here.

*February 25, 2017*

**Math**

A: If the red line has slope m1, then your line is y-5 = m1(x-3) B: If the blue line has slope m2 then your line is y = (-1/m2)(x+4) So, use the needed slopes, and massage the equations into the form y = mx+b

*February 25, 2017*

**math**

drop an altitude to KM. Note that you now have two 5-12-13 right triangles. ...

*February 25, 2017*

**Maths**

just use your GP sum formula. You have a/(1-r) = 243 a (1-r^5)/(1-r) = 242 Now divide and you have 1-r^5 = 242/243 = 1 - 1/243 . . .

*February 25, 2017*

**math**

the student walked on a heading, not a bearing. use the law of cosines. The distance d is found via d^2 = 50^2 + 200^2 - 2*50*200*cos115°

*February 25, 2017*

**math**

you should have remembered the 5-12-13 right triangle. The altitude is 12. So, the area is 5*12 = 60

*February 25, 2017*

**High School Geometry**

If SU?TP, SU=8 (think 3-4-5 triangle) Since the area is 1/2 bh using any side as a base, the other two altitudes can be found via 8*12 = 10h

*February 25, 2017*

**High School Geometry**

AC=BC = ?(3+9) = ?12 so, the perimeter is 6+2?12 or 6+4?3

*February 25, 2017*

**Math**

(68+72)/2 = 70 Or, since 70 is the average, 72 = 70+2 68 = 70-2

*February 25, 2017*

**maths**

well, 2b-3a = -(3a-2b) so you have 4(x+y)(3a-2b)-(6x+y)(3a-2b) ...

*February 25, 2017*

**math**

so, where does the slope begin, and does it drop lower when moving away from the tower, or what?

*February 25, 2017*

**Math**

The numbers in your LaTeX don't seem to agree with the "regular" section, so I'll ignore them. You want A with rows (a b) and (c d) such that 6a-b = 13 6c-d = -26 a+4b = 23 c+4d = 4 I get rows (3 5) and (-4 2) Check: http://www.wolframalpha.com/input/?i=%7B%...

*February 25, 2017*

**math**

g = b+25 b+g = 101

*February 24, 2017*

**MaTHS**

think of tan(A-B)

*February 24, 2017*

**Algebra 2**

I agree. I assume you did some math to get that idea...

*February 24, 2017*

**Maths**

L1: y = 2x+1 L2: y = (bx+5)/7 assuming that b/7 > 2, we have, using tan(A-B) = (tanA-tanB)/(1+tanAtanB) we want to find b such that (b/7 - 2)/(1+(b/7)(2)) = 1 b = -21, and we have L2: -3x + 5/7 or any parallel line with slope -3. check: arctan(-3) = 108.43° arctan(2) = ...

*February 24, 2017*

**MATHS**

well, one way is (x-h)^2 + (y-k)^2 = r^2 now plug in your values and solve for (h,k)

*February 24, 2017*

**math 4th grade**

to find the average, add up the total points and divide by the number of students: (6*100 + 4*90 + 3*80 + (26-6-4-3)*80)/26 = 86.15 I suspect a typo, since a score of 80 appears twice in the description. If so, just fix it in the expression above, and recalculate.

*February 24, 2017*

**Algebra**

x^4 = 1 = 1 cis 2? x = 1 cis 2?/4 = 1cis ?/2 Now add multiples of 2?/4 to that till you get all 4 roots. You can verify, knowing that 1^4 = (-1)^4 = i^4 = (-i)^4 = 1 Do the others in like wise.

*February 24, 2017*

**Calculus**

k is an odd name for a variable, but your answer is correct. Way to watch the integration limits.

*February 24, 2017*

**Math**

f(x) = 8-4x A f(2) = 8-4(-2) B 8-4x = 8 C Now you have two points. Draw the line connecting them D all real numbers. Think about it. Pick any x you want, and y is defined. A line goes out forever in both directions. E,F now use the graph. If it's you who has posted this ...

*February 24, 2017*

**Math**

#1. |z-1|=|z+3| |z-i|=|z+3| are both straight lines. This can be seen since |z-(a+bi)|=|z-(c+di)| |(x+yi)-(a+bi)|=|(x+yi)-(c+di)| |(x-a)+(y-b)i|=|(x-c)+(y-d)i| (x-a)^2 + (y-b)^2 = (x-c)^2 + (y-d)^2 x^2-2ax+a^2+y^2-2by+b^2 = x^2-2cx+c^2+y^2-2dy+d^2 (2c-2a)x + (2d-2b)y = c^2+d^2...

*February 24, 2017*

**Calculus II**

nope. consider {an} = 1/n The harmonic series diverges.

*February 24, 2017*

**Science**

well, you surely know that the moon is a choice. If only one choice is allowed, that must be it. If you really aren't sure about the others, you need to do some reading. google is your friend.

*February 24, 2017*

**math**

well, 2^-2 = 1/4, so -3x = -2

*February 24, 2017*

**Mathematics**

uh, which square?

*February 24, 2017*

**Math- Outcomes and Probability**

the question is the same as asking how many ways can 5 of 6 items be arranged. You will recall that that is 6P5 = 720

*February 24, 2017*

**math**

.10+.66+.08+.035 = .875 or 7/8 so, they have 1/8 left. 1/8 * 300000 = ?

*February 24, 2017*

**Math**

for angle x, the complement is 90-x: comp(x) = 90-x for angle x, the supplement is 180-x: supp(x) = 180-x So, supp(comp(x)) = supp(90-x) = 180-(90-x) = 90+x

*February 24, 2017*

**Math Word Problem**

Yes its 297 Thank you Reiny, I had a hard time understanding that one.

*February 24, 2017*

**Math Word Problem**

199 is also wrong :/

*February 24, 2017*

**Math Word Problem**

I am trying to find the exact number of male employees, thats where I am having troubles at. Like I tried, x = the number of employees x - 603 = the number of males x = 603 - x 2x = 603 x = 301.5 and it show that its wrong

*February 24, 2017*

**Math Word Problem**

67% or 603 employees in a company are female. How many are male?

*February 24, 2017*

**Mat8**

(2000*1500*1000)/(10*5*5) = 12,000,000

*February 24, 2017*

**Math**

A. f(-2) = 8-4(-2) B. 8-4x = 9 You have two points now. plot them and draw the line between them A line goes forever in both directions, both horizontally and vertically, so ... now look up the points for E and F

*February 24, 2017*

**maths(rational numbers)**

1/3 + 1/4 + 3/8 = 23/24 so, 9 hectares is 1/24 of the total...

*February 24, 2017*

**engineering mathematics**

8t + 1/2 t^2 = 18 t = 2 ?v = a * t

*February 24, 2017*

**engineering mathematics**

(300-200) = 500a

*February 24, 2017*

**engineering mathematics**

F = ma plug in your numbers

*February 24, 2017*

**Pre Calculus 30**

#1 what about zero? 9*10*10*5 #2 ok #3 as in #1, 1*10^4 #4 1000..9999 = ? #5 6P3 #6 4! * 3! #7 6 (assuming a win means matching a picture to the chosen name)

*February 24, 2017*

**cal**

There are several ways to do this. I'd google the topic. You might start here: http://whistleralley.com/torus/torus.htm

*February 24, 2017*

**K**

Using discs (washers) of thickness dx, v = ?[0,2] ?(R^2-r^2) dx where R=6-y and r=3 v = ?[0,2] ?((6-3e^(-x))^2-3^2) dx = 9?(5e^4+8e^2-1)/(2e^4) using washers of thickness dy, v = ?[3/e^2,3] 2?rh dy where r=6-y and h=2-x v = ?[3/e^2,3] 2?(6-y)(2+ln(y/3)) dy = 9?(5e^4+8e^2-1)/(...

*February 24, 2017*

**Algebra**

first, check the discriminant. If it's negative, there are no real factors. If the discriminant is a perfect square, then there are rational factors, so you can then work on finding them. 2x^2-5x+2 discriminant is 25-16=9, so we can work to find (2x-1)(x-2) the others ...

*February 24, 2017*

**Trigonometry**

you are correct so far. Of course, you have not provided any choices for selection, but the equation you need is tan? = 200/80 ? = tan-1 2.5 ? 68°

*February 23, 2017*

**Math**

#1: 20 + 4x = 140 #2: GCD(24,64,56) = 8 #3: I suspect you meant that there is a remainder of 4 when it is divided by 5. If sol, just list the numbers with these two properties: 2,5,8,11,14,17,... 4,9,14,19,... 14 = 4*3+2 = 2*5+4 #4. There are only 4 such numbers: 105,150,501,510

*February 23, 2017*

**Math**

there are 3 pairs of faces, each a rectangle. So, the area is 2(3.5*1.5 + 3.5*2 + 1.5*2) Of course, that does not include any overlap for taping things shut...

*February 23, 2017*

**Math**

the domain of all polynomials is all real numbers. f(x) = 8-4x. So, for f(-2), replace every x with -1: f(-2) = 8-4(-2) = 8+8 = 16 To graph the function, you just need two points. You already have (-2,16). So, pick any other value for x (0 is an easy one!) and plot (0,f(0)). ...

*February 23, 2017*

**Math ; Algebra**

-2x-6=-12 add 6 to both sides: -2x = -6 divide by -2: x = 3 or, -2x-6=-12 add 2x to both sides: -6 = -12+2x add 12: 6 = 2x divide by 2: 3 = x or, -2x-6=-12 divide by 2: -x-3 = -6 ... Follow the same logic for the other one and see what you get.

*February 23, 2017*

**Precal**

for this kind of problem, draw the right triangle. cos? = 2/3 means that the adjacent side is 2 and the hypotenuse is 3. sin? = ?5/3 means that the opposite side is ?5 and the hypotenuse is 3. But, then you knew that already, since the opposite side would be ?(3^2-2^2) = ?5 Si...

*February 23, 2017*

**math**

For each item, its total cost is unit-cost * no-units. So, in this case, the total cost is 6000*4 + 0.5*2050 + 5*3600 = 43025

*February 23, 2017*

**trigonometry**

recall that cos(x+y) = cosx cosy - sinx siny so, ...

*February 23, 2017*

**Math**

?PRT is isosceles ?PRT is 180-30 = 150 So, ?P and ?T are (180-150)/2 = 15° PT^2 = 1^2 + 1^2 - 2(1)(1)cos150° = 2+?3 Consider ?PQT and you can get tan T

*February 23, 2017*

**Algebra**

Try writing it as f(x) = -x(x-5)(2x-3) Now you can see that the coefficient of x^3 is negative. So, for x very large negative, say, -100, f(x) is positive. So, the graph comes down on the left, crosses the x axis at 0,3/2,5, and then continues on down to the right. So, f(x) &...

*February 23, 2017*

**Sequences Math**

x: up 1 y: down 5 so, start with y = -5x But, y(0) = -1, so y = -5x-1

*February 23, 2017*

**Geometry**

this is the other problem backwards. You need to find three numbers which add up in pairs to the given sides.

*February 23, 2017*

**Geometry**

draw the figure. Each side is the sum of the two touching radii.

*February 23, 2017*

**Physics**

PE = mgh

*February 23, 2017*

**Math**

7*8 = 5.6h

*February 23, 2017*

**Math**

The area of a parallelogram with a side of 5.6 in is equal to the area of a rectangle with sides 7 in and 8 in. Find the altitude to the given side in the parallelogram.

*February 23, 2017*

**Mathematics**

since time = distance/speed, 22.5/(x-6) + 22.5/(x+6) = 9 1/x + 1/(x+1) = 17/72 hint: 17 = 8+9 To get rid of the fraction in the denominator, invert and multiply. Then you have (x^2-16)/(x^2+5x+6) * (x^2-2x-8)/(x^2+5x+4) = (x+4)(x-4)(x+2)(x-4) ------------------------------- (x...

*February 23, 2017*

**Math**

since 15+25 = 40% did not get all correct, 24 = 60% of the class. so, ...

*February 23, 2017*

**Math**

Either side can be considered a base. So, since area = base * height, the missing side x is found via 2.4x = 3.6*4.2 Now, the perimeter is 2(4.2+x)

*February 23, 2017*

**Math**

just as with the rectangle, area = base * height

*February 23, 2017*

**MATHS**

looks more like 1/(6n-3)

*February 23, 2017*

**MATHS**

look at the denominators: 3,9,15,21,27, ...

*February 23, 2017*

**Physics - eh?**

Maybe one of the more expert physicists can decipher your convoluted sentence. I cannot.

*February 23, 2017*

**math**

because they have mass of 45.45 kg, and gravity pulls them with the force of 100 lbs.

*February 23, 2017*

**Maths**

oops. well, use the GP formulas instead. Same idea.

*February 23, 2017*

**Maths**

4/2 (2a+3d) = 312 a + a+3d = 252 now solve for whatever numbers you are interested in.

*February 23, 2017*

**Algebra**

the domain of all polynomials is (-?,+?) for rational functions, it is the same, except where the denominator is zero. f*g = (x^2+3x-4)(x+4) f/g = (x^2+3x-4)/(x+4)

*February 23, 2017*

**Calculus**

you have integral x^(1/3) dx by the power rule, that is (3/4) x^(4/3) + C Choice A is correct. In fact that is your answer, but you did not recognize it! It's always sad to get a question wrong, but to miss it when you got it right is tragic.

*February 23, 2017*

**Math - Derivatives**

huh? Let's take f=1/u. (Let u=x+1 or u=x-1) f = 1/u = u^-1 f' = -1 u-2 f" = (-1)(-2)u-3 ... fn = (-1)nn! u-(n+1)

*February 23, 2017*

**Math - Derivatives**

so, did you even think about the hint? 2x/(1-x^2) = 2x/((1-x)(1+x) = -[1/(x+1) + 1/(x-1)] The nth derivative of 1/(x+1) and 1/(x-1) is easy to figure, right?

*February 23, 2017*

**math**

well, f(0) = d so, d = -18 no idea on the values of a,b,c ... You need more information.

*February 23, 2017*

**math**

f = x^3+x^2+bx+18 f' = 3x^2 + 2x + b f'(1) = 3+2+b = 5+b Since y = -8x+20 is tangent at x=1, it has the same slope as the curve there. So, 5+b = -8 b = -13 I have no idea where a comes into play, but maybe you can work it in and include it in the solution.

*February 23, 2017*

**math**

10% discount means he paid 90%. Total cost of the goods is 1.25 * 42000 + 10*22000 = 272500 He paid 90% of that, which is 0.90 * 272500 = ?

*February 23, 2017*

**value**

many people attend.

*February 22, 2017*

**precalculus, complex numbers**

This problem is discussed here: http://math.stackexchange.com/questions/2144834/let-alpha-omega-omega2-omega4-and-beta-omega3-omega5 google is your friend. Try using it.

*February 22, 2017*

**Math**

4 small cubes will fit into a 1-ft length. So, 4^3 = 64 small cubes will fit into each cubic foot. 64*77 small cubes fit into 77 ft^3. Assuming the dimensions of the large solid are multiples of 3 inches ...

*February 22, 2017*

**Math**

at least 40" tall means that h >= 40 So, those who cannot ride are less than 40, or h < 40 Not <= 40, since the 40" kids can ride.

*February 22, 2017*

**maths**

you can construct a right angle by constructing a perpendicular bisector. Or, google will show you many other ways. Then just measure your distances.

*February 22, 2017*

**Math. Fair race project help!**

Looks to me like man: 45t the anime elk is just a cartoon, so its speed doesn't matter ... why the emphasis on a fair race? Is someone cheating?

*February 22, 2017*

**Maths**

7/2 (2a+6d) = 13/2 (2a+12d) 7a+21d = 13a+78d 6a + 57d = 0 2a + 19d = 0 S20 = 20/2 (2a+19d) = 0

*February 22, 2017*

**Maths**

If you mean log(9^3/4^3), it is certainly not log2 If not, try fixing it up with real math notation, so we can see what you do mean...

*February 22, 2017*

**math**

see related questions below.

*February 22, 2017*

**Differential equations,Calculus**

yes, c=k, so if k = 5?/4, t = k (1 - 1/r) = 5?/4 (1 - 1/r)

*February 22, 2017*

**maths**

huh. the numbers are 5x and 7x, but 7 does not divide 120. ???

*February 22, 2017*

**computer programming**

for i=1 to 10 read n[i] for i=10 to 1 step -1 print n[i] Or, if you don't like counting down, for i=1 to 10 print n[11-i] or, depending on the language, the array may be 0-based, but you can allow for that.

*February 22, 2017*

**Math**

density is people/mi^2, so just divide the population by the area...

*February 22, 2017*

**Algebra**

so, it is 10^6 as big, or a million times.

*February 22, 2017*

**Physics**

conserve momentum: 0.5*10 + 0.5*0 = (0.5+0.5)*v And Lose All Of Those Ridiculous Capital Letters!

*February 22, 2017*

**math**

Note that each fraction is of the form n/(2n+1) This can be written as 1/2 - 1/(2(2n+1)) clearly, as n gets larger, a smaller amount is subtracted, so the fraction with the largest denominator is the largest -- closer to 1/2

*February 21, 2017*

**parabolas**

42

*February 21, 2017*

**Calculus**

let x = 4tan? ?(16+x^2) = 4sec? dx = 4sec^2? d? it gets much simpler.

*February 21, 2017*

**Calculus**

let x = 5 sec? dx = 5 sec? tan? ?(x^2-25) = 5 tan? x^2 = 25 sec^2? Things will get much simpler.

*February 21, 2017*

**Algebra**

the angles are x, 4x+2, 3x-6 they add up to 180, so ...

*February 21, 2017*

**Math**

note the pattern. 9 is 8+1, so: 9*1 = 8*1 + 1 9*2 = 8*2 + 2 ... 9*7 = 8*7 + 7

*February 21, 2017*

**Algebra**

If it takes Joe x minutes alone, then 1/35 + 1/x = 1/15

*February 21, 2017*