Saturday
February 25, 2017

Posts by steve

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

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