Thursday
June 30, 2016

Posts by steve

Total # Posts: 41,518

Algebra 1
2x+4 <= 14 2x <= 10 x <= 5 so, 5 is the largest possible number. 2*5+4 = 14. Any number larger than 5 makes the expression more than 14.
June 3, 2016

Math-Calc
see earlier post
June 2, 2016

Calc-Math
If you don't even know where to begin, you must not have read the section on this topic. It says that the limit of f(x)/g(x) = f'(x)/g'(x) so, your limit is just (ln3 * 3^x - ln6 * 6^x)/1 = (ln3-ln6) = ln(3/6) = -ln2
June 2, 2016

calculus
without calculus, the distance from the point to the line is |4(-2)+2(-1)+5|/√(4^2+2^2) = √5/2 Using calculus, we have the distance z from (-2,-1) to (x,y) is z^2 = (x+2)^2 + (y+1)^2 But y = -(4x+5)/2, so z^2 = (x+2)^2 + ((-(4x+5)/2)+1)^2 z^2 = 5x^2 + 10x + 25/4 z...
June 2, 2016

Geometry
The x=15 is ok Not sure what the last set of values is for, but if they are for the 1st problem, no good. x^2 + (5-x)^2 = 25 x^2 + x^2-10x+25 = 25 2x^2-10x = 0 2x(x-5) = 0 x = 0 or x=5 So, the points of intersection are (0,5) and (5,0)
June 2, 2016

Geometry
well, y = 5-x, so x^2 + (5-x)^2 = 25 now just expand and solve the quadratic.
June 2, 2016

Algebra
x^3-5x^2+2x+8 ----------------- = x^2-3x-4      x-2
June 2, 2016

Geometry
right
June 2, 2016

Geometry
Assuming a typo, and you meant PN, we have PM/ZX = PN/ZY so, (x+5)/30 = (4x-10)/75 Now just solve for x.
June 2, 2016

Calculus
I just noticed that you did not specify that the y-axis formed part of the boundary. Without that condition, the horizontal strips extend leftward forever. Of course, you may have mixed up x and y in places, so ...
June 2, 2016

Calculus
This is most easily done by integrating on y, using horizontal strips. a = ∫[-1,3] x dy = ∫[-1,3] (8+2y-y^2) dy
June 2, 2016

Math(Assignment due today)
sounds like the ramp rises at a 4.7° angle, so it's ok.
June 2, 2016

Pre-Calculus
enter your coefficients at the url below to see all the details: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
June 2, 2016

Polynomials and properties of exponenets
I get AC?BD
June 2, 2016

Mathematics
if the quiz is counted more than the other grades, things get more complicated. If the quiz counts as much as all the rest, then the final grade would be (88+95)/2 = 91.5 I suspect there is missing information here.
June 2, 2016

Physics
they both travel with the same speed. So, a longer wavelength means it oscillates more slowly. Recall that v = λf 3λ means f/3 to get the same v.
June 2, 2016

Pre-Calculus
next time, show your work, so we can find your error. From equation 1, x = 2y-5 plug that into #2, and you have x^2+y^2 = 25 (2y-5)^2 + y^2 = 25 5y^2 - 20y + 25 = 25 5y(y-4) = 0 y = 0 or 4 now you can find x values as needed, from either equation. http://www.wolframalpha.com/...
June 2, 2016

Polynomials and properties of exponenets
D,A,C,D Looks like some serious review is in order.
June 2, 2016

Geometry
Time to review the special angles: sin(30°) = 1/2 so, √sin(30°) = 1/√2 also, cos(30°) = √3/2
June 2, 2016

algebra
Reiny responded to this earlier, at http://www.jiskha.com/display.cgi?id=1464879381 If you want to pin it down more, there must be some other constraints.
June 2, 2016

Pre-Calculus
you got c correct, but did not express the coordinates of the foci. c = ±5 where is the center of the ellipse? Is the major axis horizontal or vertical?
June 2, 2016

Math
correct
June 2, 2016

Pre-Calculus
you are correct as far as you went, but recall that n*ln(x) = ln(x^n). 2lnx - 6lny + 1/3ln e^12 = ln(x^2) - ln(y^6) + (1/3)(12) = ln(x^2/y^6) + 4 = ln(e^4 x^2/y^6)
June 2, 2016

5th Grade Math - Urgent Part II
1,000,000 is the only number with prime factorization 2^6 * 5^6 = (2*5)^6 = 10^6 64 is 2^6 but has no factors of 5.
June 2, 2016

Pre-Calculus
your function is just a polynomial. The domain of all polynomials is (-∞,∞)
June 2, 2016

algebra
since distance = speed * time, 6x + 6(x-20) = 624
June 2, 2016

MATH
They gave you the functions. Did you graph them as suggested? Here are the lines: http://www.wolframalpha.com/input/?i=plot+y%3D25%2B10x+,+y+%3D+18%2B15x Now you can surely answer the questions.
June 2, 2016

Trigonometery
no one is assigned to sit here and watch for problems. We have lives, too, and when we get a chance, we check in. As you know, the function a sin(kx) has amplitude a and period 2pi/k, so you can use your requirements to produce the function -4sin(8x) But you probably figured ...
June 2, 2016

match
apparently you have knowledge about ditches and absorption rates which you have not shared here.
June 2, 2016

Calculus
So, each square has base and height e^-x Thus, the volume, adding up all those thin squares, is ∫[0,2] (e^-x)^2 dx = ∫[0,2] e^(-2x) dx let u = 2x, and that becomes (1/2)∫[0,4] e^-u du ...
June 2, 2016

Physics
wrong
June 2, 2016

math
(1+r)^12 = 2 r = 2^(1/12)-1
June 2, 2016

Math
I assume you really meant 1/(x-1)+1/(x+1) ------------------ 1/(x-1)-1/(x+1) cross-multiply to put top and bottom over a common denominator of (x-1)(x+1) Then since the same denominator occurs top and bottom, it can be discarded, just as (2/3)/(5/3) = 2/5 now you have (x+1)+(x...
June 2, 2016

Math
gibberish
June 2, 2016

Maths
kx^2-5x+k is not a cubic polynomial.
June 2, 2016

physics
Since F=ma, the acceleration of the car is 1/5 gravity. So, how long does it take the car to move 20cm, under (1/5)g acceleration? s = 1/2 at^2
June 2, 2016

Math Please Help Quick
.20 * 20 = ?
June 2, 2016

math
t+r = 800 (3/4)t + (5/6)r = 800-192 to find r, substitute for t: (3/4)(800-r) + (5/6)r = 608 (1/12)r + 600 = 608 r/12 = 8 r = 96
June 2, 2016

math
if you google manual cube roots, you will find several nice explanations of how to extract roots by hand. It's not worth the effort, since calculators are so handy these days. Use your calculator to evaluate 36.13^(1/3) power
June 2, 2016

maths
draw a diagram. review your basic trig functions. Now it is clear that 2.5/x = cos60° now just solve for x, the length of the ladder.
June 2, 2016

Math Year 10 - Simultaneous equations
c = 2s 2c+4s=104 now solve for c
June 2, 2016

Mathematics
It'd be nice to have some of your work to look at, eh? 3/x + 5/y = 4 9/x + 4/y = 5 It gets messy to try and solve for x or y, so solve for 1/x instead. 1/y = (4-3/x)/5 thus, 9/x + 4/5 (4-3/x) = 5 45/x + 16 - 12/x = 25 33/x = 9 1/x = 9/33 = 3/11 so, x = 11/3 now plug in to ...
June 2, 2016

Figurs and Numbers
12% = 0.12 spending means that amount is subtracted. So, subtract .12 twice. Having done that, subtract another 25% = 0.25, and the remainder is 2010. Then find x, the original amount which leaves that remaining amount. Finally, knowing x, 25% of 57% of that amount is what was...
June 2, 2016

Figurs and Numbers
x(1-.12-.12)(1-.25) = 2010 .76*.75x = 2010 x = 3526.32 x * .76 * .25 = $670.00 on education
June 2, 2016

Pre-Calculus
well, it could be (x+1)(x-7)(x^2-2) = what you wrote. extra credit: are there any others?
June 2, 2016

Geometry
I agree. It looks like a syllogism, but there are too many things wrong.
June 2, 2016

Sxiences
recall that F = ma now just plug in your numbers to get m.
June 1, 2016

Spanish
correct
June 1, 2016

MAth
simple interest: 200*.06*2
June 1, 2016

Chemistry
depreciation
June 1, 2016

Chemistry
two errors, DrRebel: (0.693/3.8) ≠ 0.8663 it was 98.4, not 94.4
June 1, 2016

Chemistry
98.4 * (1/2)^(19/3.8) = 3.075 g
June 1, 2016

Mathematics
for the perimeter, since p = 2(length+width) p is even, since it is a multiple of 2.
June 1, 2016

Algebra
How much more is 9 than 7? You do it by finding the difference: 9-7 so, do this the same way: (9x+8)-(5x+6) ...
June 1, 2016

math
divide that by 2, since it takes two hands to shake once.
June 1, 2016

Math
x:9=2/3:36 x*36 = 9 * 2/3 36x = 6 x = 1/6 = 0.1666 or, x/9 = (2/3)/36 x/9 = 2/108 x/9 = 1/54 x = 9/54 = 1/6 maybe you should try some other proportions with less complicated numbers, to learn the method and why it works.
June 1, 2016

Math
you have to subtract the width of the frame, both top and bottom. The remaining height is occupied by the picture 5 2/3 * 2 = 10 4/3 = 11 1/3 now subtract that from the overall height, and you have 25 5/6 - 11 1/3 = 25 5/6 - 11 2/6 = 25-11 + 5/6 - 2/6 = 14 3/6 = 14 1/2
June 1, 2016

Science - Chemistry
Kind of depends on the size of the diamond, wouldn't you say?
June 1, 2016

Math please help
note that as x grows by 2, y falls by 1. That gives you a slope of -1/2. So, start with y = -1/2 x But, if you plug in x=2, that gives y = -1/2 (2) = -1 But in fact, y=1. So you need to add 2, giving you y = -1/2 x + 2 or, y = (4-x)/2 Use the other values of x and y to see ...
June 1, 2016

Pre-Cal: Plz help!
Go to Reiny's url and tweak the input until it agrees with what you intended. It's probably just a combination of typos.
June 1, 2016

math
me either, but recall that 1L = 1000cm^3, so find your volume in cm^3 and divide by 1000
June 1, 2016

Pre-Cal
The answer makes me think you are trying to find the derivative of ∛(x^2+3)/x = ∛(x^2+3) * x^-1 That would be ∛(x^2+3)*(-1)(x^-2) + (1/3)(x^2+3)^(-2/3) * (2x)(1/x) To put all that over (x^2+3)^(2/3), multiply the first term, and you get (x^2+3)(-1/x^2) + (1/3...
June 1, 2016

MATH
clearly, E=T+1 because of the carry. So, T is 1,5,6 G is even (since it is N+N), so it is 2,6 Now just a little trial and error yields 671 +51 ------ 722
June 1, 2016

MATH
If you were not given letters for the answer, then just pick any values you want!
June 1, 2016

algebra
so, even though Bosnian started out with a yes his work shows that the answer was D, not A.
June 1, 2016

Algebra
can you not plot the points and draw a curve through them? Note that as x grows by 1, y drops by 1/2 of its value. So, it looks like y = 10 * 2^-x an exponential curve.
June 1, 2016

Pre-Calculus
vertical asymptotes occur where the denominator is zero and the numerator is not. So, your graph has a vertical asymptote at x=0 try entering your function at wolframalpha.com to see its graph, and other information. Note that as long as x≠4, f(x) = 1/x There is a hole ...
June 1, 2016

Physics
since time = distance/speed, 50/75 + x/45 = 9/4 You live 50+x miles away.
June 1, 2016

math
since (10^-8)^3 = 10^-24,that would be ∛36.31 * 10^-8
June 1, 2016

math
just solve the inequalities to see which has the smallest solution. remember that for fractions, a larger denominator means a smaller quotient. So, for example, if w>4, w+2 > 6, so 4/(w+2) < 4/6 = 2/3 reason similarly for the others.
June 1, 2016

Math help plz??
time = distance/speed, so 3.54x10^7 / 3x10^8 = 1.18x10^-1 or, 0.118 seconds
June 1, 2016

math
you can play around with this stuff at http://davidmlane.com/hyperstat/z_table.html
June 1, 2016

Maths
(x+y)/2 = 7 xy/3 = 16 y=48/x x+48/x = 14 x^2-14x+48 = 0 (x-6)(x-8) = 0 x and y are 6 and 8
June 1, 2016

Polynomials
mine, too.
June 1, 2016

maths
or, you could just solve the two equations using the quadratic formula. That would yield x = [3y±√(5y^2-4)]/2 x = [y±√(152-35y^2)]/6 equate those two and you get y=±2
June 1, 2016

maths
I am assuming you want to solve the system of equations x^2-3xy+y^2+1 = 0 3x^2-xy+3y^2 = 13 from the second, we have xy = 3x^2+3y^2-13 using that in the first, we have x^2-3(3x^2+3y^2-13)+y^2+1 = 0 x^2-9x^2-9y^2+39+y^2+1 = 0 -8x^2 - 8y^2 = -40 x^2 + y^2 = 5 Using that in ...
June 1, 2016

math plz help ;-;
these two make substitution the method of choice. x+y=2 means y = 2-x So, using that in the other equation, 2x-(2-x) = 10 2x-2+x = 10 3x = 12 x = 4 now use either equation to see that y = -2 check: 2*4-(-2) = 8+2 = 10 4+(-2) = 4-2 = 2 similarly, you can substitute for x: x = 2...
June 1, 2016

Precalculs
regardless of the base, log(1) = 0, because x^0 = 1 so, what you have is 6x-12 = 0 x = 2 try writing log_x(n) for log of n (base x). The underscore indicates the base.
June 1, 2016

Math-Calc
you could write f(x) = 7*ln(x^2+5)^-1 then, using the power and chain rules, f'(x) = 7*(-1)*ln(x^2+5)^-2 * (2x) = -14x/ln(x^2+5)^2 f'(1) = -14/(ln6)^2
June 1, 2016

Radicals3
x√(12x^4) = x√(4x^4*3) = x(2x^2)√3 = 2x^3√3 3x√x^2 * 2√x^5 = 6x√(x^2*x^5) = 6x√(x^6 * x) = 6x*x^3 √x = 6x^4 √x -7 = 2-√(12x-3) -9 = -√(12x-3) 81 = 12x-3 84 = 12x x = 7
May 31, 2016

Radicals2
9√72 / 2√24 = 9√(3*24) / 2√24 = 9√3√24 / 2√24 = 9√3/2
May 31, 2016

Radicals
∛-192 = ∛(-1*64*3) = -1*4*∛3 -6∛13) = ∛((-6)^3*13) = ∛(-216)(13) = ∛-2808
May 31, 2016

math plz check ;-; sorry
by definition, (√47)^2 = 47 just as √2 * √2 = 2 (√x)^2 = x That is the definition of the square root of x: the number which, when squared, produces x.
May 31, 2016

math plz check ;-; sorry
so, you're saying that 47 > 50 ?
May 31, 2016

math
one way is just to compute the equations of the lines joining the pairs of points, and show that they intersect in the same point. On the unit circle, let P1 = (1,0) P2 = (cos pi/9,sin pi/9) ...
May 31, 2016

Math
In your equation, p and q are vectors so, find where the y-component is zero.
May 31, 2016

math plz check ;-;
so, you're saying that 47 > 50 ?
May 31, 2016

Algebra
first step: lose the mixed numbers! 5/6-2(-1 3/4)/5 1/5 = 5/6-2(-7/4)/(26/5) = (5/6) + (14/4)*(5/26) = 5/6 + 35/52 = 235/156
May 31, 2016

tripz
This kind of thing is what log tables were used for. Now we have calculators.
May 31, 2016

Statistics
you can find this and other cool answers at http://davidmlane.com/hyperstat/z_table.html
May 31, 2016

Math
He has 9*68=612 points so far He needs 10*70=700 points to achieve his desired average So, haw many more points does he need?
May 31, 2016

Math(Reiny Please Help)
is there something unclear about the solution at http://www.jiskha.com/display.cgi?id=1464662427 ??
May 31, 2016

Math
(4x^2 - 2x-1) - (-3x^3 + 2) 4x^2 - 2x - 1 + 3x^2 - 2 7x^2 - 2x - 3
May 31, 2016

physics
solve for t in 0.5 - 0.05t = 0
May 31, 2016

Trignometry
maybe you can fix the problem. As it stands, you have mixed up a trig function and the angle: tan(theta+alpha) + 2alpha
May 31, 2016

Math
the area of a circle with radius 15 is pi r^2 = 225pi
May 31, 2016

math
that would be 3(2y) + 1(y+3) = 6y+y+3 = 7y+3
May 31, 2016

math plz help ;-;
the equation of your line is y-8 = -3(x+4) Now massage that to see which choice it matches.
May 31, 2016

math plz help ;-;
plug in the points for your equation: (-4,8): -3(8) = -4-4 -24 = -8 BZZZT! Try again (1,-7): -3(-7) = 1-4 21 = -3 BZZZT! Not that one either.
May 31, 2016

Physics
start: a = v/t = 36km/hr/10s = 3.6 km/hr/s you can convert km/hr to m/s if you desire the usual m/s^2 value. to stop takes twice as long, so a = 1/2 as much.
May 31, 2016

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