Tuesday
March 31, 2015

Posts by steve


Total # Posts: 30,232

Math--MS SUE!
#1 24 #2 46 #3 70
March 28, 2015

Math
Good job, Reiny. I keep seeing 3^√ being used as cube root, so maybe I was way off. In any case, the problem is solved.
March 28, 2015

Math
let f(x) = x^3 - 7 so f(∛7) = 0 See http://keisan.casio.com/exec/system/1244946907 just enter your function, its derivative, and initial guess.
March 28, 2015

Earth Space Science
you are correct.
March 28, 2015

statistics
so, do you have a table of NBA players' heights? If so, just do what the exercise says.
March 28, 2015

Math
I get XB=6 How far do you get? Hint: parallel lines indicate similar triangles.
March 28, 2015

Trigonometry
Usage differs, but one of them is the single value -π/3, and the other is -π/3+nπ check your text to see what is expected of you.
March 28, 2015

Trigonometry
just factor the first one, then there will be two values between 0 and 2π, and all multiples of 2π added thereto. 2sin^2(x)-5 sin(x)-3=0 (2sinx+1)(sinx-3) = 0 sinx = -1/2 sinx = 3 (not a valid solution) The other is already factored: (cos(x)-((√2)/2))(sec(x)-1...
March 28, 2015

Trigonometry
tan(-π/4) = -1 so, θ = -π/4 + nπ sin(π/6) = 1/2, so θ/2 = π/6,5π/6,... θ = π/3, 5π/3, ... = π/3 + 4nπ, 5π/3 + 4nπ
March 28, 2015

Trigonometry
(2sinx-√3)(2sinx+√3) = 0 sinx = ±√3/2 x = π/3, 2π/3, 4π/3, 5π/3 cos(3x) = -1 so 3x = π,3π,5π x = π/3, π, 5π/3
March 28, 2015

Math
my answer is D
March 28, 2015

Math
A gardener is mowing a 20 by 40 yard rectangular pasture using a rectangular pattern. He mows from one corner of the pasture to the corner diagonally opposite. What is the length of this pass with the mower? Give your answer in simplified ,form. a- 10 sq root 20 b- 20 sq root ...
March 28, 2015

math
2x*5x = 40 So, find x, and then 5x.
March 27, 2015

math
f(x) = 2(x-1)^2 - 7 So, if we restrict the domain to x>1 or x<1 we can find an inverse I expect you can turn that info into an interval . . .
March 27, 2015

math
Since referring you to the related questions seems to do no good, here it is again: f(x) = cx/(2x+3) f(f) = cf/(2f+3) = c[cx/(2x+3)]/(2[cx/(2x+3)]+3) = c^2x/(2(c+3)x+9) So, if c^2x/(2(c+3)x+9) = x, c^2x = 2(c+3)x^2 + 9x 2(c+3)x^2 + (9-c^2)x = 0 x(2c+6+9-c^2) = 0 x(15+2c-c^2...
March 27, 2015

math
Looks to me like g*62 + (75-g)*56 = 75*58 Or, since we're looking for the number of boys, not girls, 56b + 62(75-b) = 58*75
March 27, 2015

Math
thank you
March 27, 2015

Math
my answer is 5m
March 27, 2015

Math
Tasha is planning an expansion of a square flower garden in a city park. If each side of the original garden is increased by 7m the new total area will be 144m^2. Find the length of each side of the original garden.
March 27, 2015

Math
What is the value of c so that y=x^2+15x+c is a perfect square trinomial?
March 27, 2015

Algebra 1
Use the graph of f(x) to find the solutions to the equation f(x)=0 a-2 -10 & 2 b_ 2 10 & -2 c- 1 10 d- no solutions
March 27, 2015

Algebra 1
thank you
March 27, 2015

Algebra 1
a boulder is thrown launched into the air with an upward velocity of 184 ft per second. Its height h in feet after t seconds is given by the function h(t)=-16t^2 +184t+6. How long does it take the boulder to reach its maximum height? What is the boulder maximum height? a- 11.6...
March 27, 2015

Algebra 1
Thank you very much at 68 trying to help grandson I'm stretching a bit to when I took this
March 27, 2015

Algebra 1
so it would be 22 ft after 1 second
March 27, 2015

Algebra 1
a ball is thrown into the air with an upward velocity of 32 ft per second. Its height h in feet after t seconds is given by the function h(t)=-16t^2 +32t+6. How long does it take the ball to reach its maximum height? What is the balls maximum height? a- 22 ft 1.0 second b- 22 ...
March 27, 2015

Math
well, just multiply them. If you get the identity matrix, they are inverses Looks like we have a winner! http://www.wolframalpha.com/input/?i=%7B%7B1%2C1%2C1%7D%2C%7B3%2C5%2C4%7D%2C%7B0%2C-1%2C0%7D%7D*%7B%7B4%2C-1%2C-1%7D%2C%7B0%2C0%2C-1%7D%2C%7B-3%2C1%2C2%7D%7D
March 27, 2015

Algebra 1
244 was on the wrong problem - this one was 0 sorry
March 27, 2015

Algebra 1
review the discriminant. If it is positive, there are two real roots. In this case, b^2-4ac = 0, so there is but one root. -8x^2-8x-2 = -2(2x+1)^2 How ever did you come up with a discriminant of 244?
March 27, 2015

Algebra 1
I figured the discriminant at 244 so infinite?
March 27, 2015

Algebra 1
How many real number solutions does the equation have? -8x^2-8-2=0 o solutions 1 2 infinitely many I get -1/2 so would it be 2?
March 27, 2015

Algebra 1
thank you
March 27, 2015

Algebra 1
A physics student stands on top of a hill that has an elevation of 56 meters. He throws a rock and it goes up into the air and then falls past him and lands on the ground below. The path of the rock can be modeled by the equation - y=-0.04x^2+1.3x+56 where x is the horizontal ...
March 27, 2015

Algebra 1
your right sorry y=-0.04x^2+8.3x+4.3
March 27, 2015

Algebra 1
A model rocket is launched from a roof into a large field. The path of the rocket can be modeled by the equation- y= -0.04x^2+8.3x,where x is the horizontal distance, in meters, from the starting point on the roof and y is the height, in meters of the rocket above ground. How ...
March 27, 2015

Algebra
You can also solve it without finding the value of k. Since xy is constant, 150y = 4*300
March 27, 2015

vector algebra
your operations make no sense u.v is a scalar, so (u.v)xv is undefined naturally, vxv=0, so u.vxv = 0 if u is a vector, what does u^2 mean?
March 27, 2015

ALgebra
see related question below
March 27, 2015

math
he was a midget.
March 27, 2015

math
(30 * 3 3/4)/20 = 5 5/8 so, how many whole bolts?
March 27, 2015

programming concepts
to find the average, just add up all the numbers and divide by how many there are. That means you have to count them as you read them.
March 27, 2015

Math
cool. Look. We don't mind helping find answers, but at least can we expect not to have to provide the question as well?
March 26, 2015

Math Venn Diagram
Did you make a Venn diagram yet? Put any numbers in it? Start with the 4 in the middle. Then work your way out from there.
March 26, 2015

Math
4*6*(5-x) = 2*4*6* 5-x = 2 x = 3
March 26, 2015

Math
9*pi*1.2 units/min
March 26, 2015

geometry
yep. so stipulated.
March 26, 2015

Math
9*3.77 units/min
March 26, 2015

pre algebra
well, how much after one payment?
March 26, 2015

Physics
If A is moving in the positive direction, then we must have zero total momentum before and after the collision: 10(15) + m(-5) = 0
March 26, 2015

math
well, if the original radius is r, we have π(r+1)^1 = 100π Or, just note that it's obvious that a radius of 10 gives an area of 100π, so the original radius was 9.
March 26, 2015

Math 115
You have any thoughts on any of these?
March 26, 2015

Math 115
If the cheap sides are x, and the expensive side is y, then xy = 320 c(x) = 6*2x + 6y + 14y = 12x+20y = 12x + 20(320/x) c'(x) = 12 - 6400/x^2 minimum cost is at x = 80/√12 ≈ 23 So, the area is roughly 23 by 14 (That's 322 ft^2)
March 26, 2015

Math 115
P = R-C that will be a parabola. Find its vertex.
March 26, 2015

Math
Look. If I said I had to pick 10 apples, but I only had 7 so far, how would you decide the number I still needed? Don't let the fractions scare you. They're just numbers.
March 26, 2015

Math
subtract what he has from the total.
March 26, 2015

math
f(x) = cx/(2x+3) f(f) = cf/(2f+3) = c[cx/(2x+3)]/(2[cx/(2x+3)]+3) = c^2x/(2(c+3)x+9) So, if c^2x/(2(c+3)x+9) = x, c^2x = 2(c+3)x^2 + 9x 2(c+3)x^2 + (9-c^2)x = 0 x(2c+6+9-c^2) = 0 x(15+2c-c^2) = 0 x(5c-1)(3c+1) = 0 So, c = 1/5 or c = -1/3
March 26, 2015

Algebra
f(x) = 2(x-1)^2 - 7 So, if we restrict the domain to x>1 or x<1 we can find an inverse
March 26, 2015

math
h = 1/√x h^2 = 1/x x = 1/h^2 so, h^-1(x) = 1/x^2 h^-1(4) = 1/16
March 26, 2015

algebra
since g(x) is a parabola, there are two values of x for every value of g. So, there is no inverse. However, if you pick a single branch of the parabola (that is, you restrict the domain), there is an inverse.
March 26, 2015

Math
Convert 22 miles to yards. Use a proportion to solve. Show your work. Where do I start with this problem?
March 26, 2015

calc
f is a polynomial, so it is continuous and differentiable f(4) = f(0) = 8, so that's ok So, you want c where f'(c) = 0 That means you need 3c^2 - 2c - 12 = 0 c = 2.361 The other value is not in [0,4]
March 26, 2015

Math
starting from M, you go 74 SE and 42 W That is (52.33,-52.33) + (-42,0) = (10.33,-52.33) tanθ = -52.33/10.33 = -78.8° So, the bearing is 168.8° or E 78.8° S or S 11.2° E
March 26, 2015

5th grade math
80 <= 1.22n <= 85 divide through by 1.22 and you get 65.57 <= n <= 69.67 If you want only integer values for n, then that would be any of 66,67,68,69
March 26, 2015

geometry
not sure how I'd do it without trig. Any clever geometric relationships that make it easy?
March 26, 2015

geometry
in triangle PQS. sinP/9 = sinQ/8 = sinS/5 So, you can find angle P Now, using the law of cosines in triangle PRT RT^2 = 10^2 + 16^2 - 2*10*16*cos(P)
March 26, 2015

calculus
p(8) = 1536 p(4) = 192 so, avg v is (1536-192)/(8-4) = 336 p'(t) = 9t^2 so, you want 9c^2 = 336
March 26, 2015

7th grade math (probability)
They all look good to me.
March 26, 2015

math
Huh? You said above what the vertex is. as always, it is at t = -b/2a It is not at t=3, but very close. Probably good enough.
March 26, 2015

math
clearly there is an x-intercept somewhere just beyond 6. See how the height is descending. Since the given h values do not show an obvious symmetry, it is not immediately clear where the vertex is. However, since h(0) = 0, if h(t) = at^2 + bt + c c = 0, so h(t) = at^2 + bt ...
March 26, 2015

math
try writing fractions like this: 2/3 + x/4 = 4/7
March 26, 2015

Algebra
two real roots
March 26, 2015

Math
well, just work from the inside out 2/3 - 1/3 = 1/3 so, what you have without the brackets is 1/3 * 5/8 = 5/24
March 26, 2015

Math
1 yd = 3 ft (1 yd)^3 = (3 ft)^3 = 27 ft^3
March 26, 2015

Algebra 1
(66-6)/6 = 10 (77-7)/7 = 10
March 26, 2015

^math^
√(19-4√21) since 21 = 19+2, I'd check (2-√21)^2 = 4-4√21+21 nope (1-2√21)^2 = 1-4√21+42 nope (2√3-√7)^2 = 12-4√21+7 aha!
March 26, 2015

MATH
.08x - .05(36000-x) = 2750
March 26, 2015

algebra
simple interest, yes compound interest, no
March 26, 2015

math
didn't my solution in the related question below do the job?
March 26, 2015

math
-3 It helps a bunch if you use a caret (^) to indicate exponents. As in (10^6)^-3 = 10^-18
March 26, 2015

science
1st step: figure how many moles of each you have. Then figure the fraction.
March 26, 2015

math
well, you know the formula for the area of a triangle, so plug in your numbers 30h/2 = 600
March 26, 2015

algebra
for substitution, I would, um, substitute. The 1st equation tells you that y = -2x So, substitute that into the 2nd equation to get x-3(-2x) = -7 x+6x = -7 7x = -7 x = -1 Now you can find y. As for elimination, 3x + 4y = 1 5x – 3y = 21 to eliminate y, multiply the 1st by ...
March 26, 2015

Geometry
just solve 2(3x+10 + x+12) = 76 then you can figure the length and width, and thus the area.
March 26, 2015

math
see related question below
March 26, 2015

Math
just as you would any quadratic: 1.862t^2 - 50t - 2 = 200 1.862t^2 - 50t - 202 = 0 t = (50±√(50^2 - 4(1.862)(-202)))/(2*1.862) = (50±√4004.496)/3.722 = (50±63.281)/3.722 = -3.566 or 30.419
March 26, 2015

math
the dimensions are x,y,3
March 26, 2015

Math
false 6x1 You can only multiply two matrices if the columns of the 1st are the same as the rows of the second. That is, the dimensions must be of the form axb and bxc a and c may be anything, but the b's must match. The result is axc.
March 26, 2015

Math
just solve 2^(-t/1590) = 1/5 since 2^-2 = 1/4, you should expect an answer something more than two half-lives.
March 26, 2015

Math question
33+55-14 = 74 students liked something That means 26 liked nothing So, the number not liking orange is 26+(76-33) = 69 How did you arrive at 67? As usual, check my math
March 26, 2015

math
(1060-560)/1060 * 100 = 47%
March 26, 2015

Calculus 2 (Differential Equation)
If we pick a different c, the solution looks a little more symmetric, and more like the original equation: y = sin(arcsin(x)+arcsin(c)) y = sin(arcsin(x))cos(arcsin(c)) + cos(arcsin(x))sin(arcsin(c)) = x√(1-c^2) + c√(1-x^2) Just a thought. A bit ugly because c ...
March 26, 2015

Math
2m = 200 cm so, subtract the 15, and what do you have left?
March 26, 2015

Physics
since 1A = 1C/s, you have a current of 1C/.09s = 11.11 amps now just recall your formulas for power and energy
March 25, 2015

Math if my answer is correct
I get -0.04 and 26.89 what did you do to get your answers?
March 25, 2015

Math
That's what I get
March 25, 2015

algebra
It can indeed be either, depending on whether you are given a set of six letters, or allowed to choose your own six from the whole alphabet.
March 25, 2015

physics
how long does it take to fall? 4.9t^2 = 310 so, its downward speed is v = 9.8t
March 25, 2015

algebra
y >= 4x-5 For inequalities, the solution is a whole set of numbers, not just one. Plot the line y = 4x-5 Your inequality as as its solution everywhere in the whole x-y plane which is above that line, since that is where y is greater than the values lying on the line. The ...
March 25, 2015

math
since 72° is 1/5 of 360°, 3 slices is 1/5 of the pie. That help? The real question is, how the heck do you cut a pie into an odd number of equal slices?
March 25, 2015

physics
F = ma what's the trouble? Forget your Pythagorean Theorem?
March 25, 2015

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