Monday
December 22, 2014

Posts by steve


Total # Posts: 27,667

Algebra
I'll do one, and you try the other. 2x^2+7x = 4 (x^2 + 7/2 x) = 2 (x^2 + 7/2 x + (7/4)^2) = 2 + (7/4)^2 (x + 7/4)^2 = 81/16 x + 7/4 = ±9/4 x = -7/4 ± 9/4 x = -4 or 1/2 Just recall that (x+a)^2 = x^2 + 2ax + a^2 That's why I added (7/4)^2 to both sides. ...
November 7, 2014

science Help 911!!
Looks good to me.
November 7, 2014

ALakh narayan sing high school Ekma saran
1/6(2x+3y)+x/3=8 1/2(7y-3x)-y=11 Rearranging things a bit to get rid of the bothersome fractions, we have 4x+3y = 48 -3x+5y = 22 Since y = (48-4x)/3, -3x+5(48-4x)/3 = 22 Or, -9x+240-20x = 66 29x = 174 x = 6 Now you can easily find y.
November 7, 2014

algebra - incomplete
I think you are missing a t in the formula.
November 7, 2014

multiplying integers
10^2 = 10*10 = 100 So, -10^2 = -100 Powers are done before multiplication. SO, the expressions is evaluated as -(10^2), NOT (-10)^2, which is (-10)(-10) = +100
November 7, 2014

algebra
no, it would never be positive. multiplying two negatives always gives a positive. That third negative then yields a negative product.
November 7, 2014

MATH
#1 -15 - (-5.6) = -9.4 #2 ...
November 6, 2014

Programming (Integer generator)
Ignoring the syntax error of the missing close brace, all you do is set the text to the latest string displayed. All the other strings are replaced. You need to append a new line for each value of i, not just do a clean reset of the text area each time.
November 6, 2014

algebra help!
The domain is the set of 1st values from the pairs: (b) In #2 you are correct.
November 6, 2014

Algebra
The slope of the line is 2, so y-a^2 = 2(x-a) y = 2x+(a^2-2a) 2(-3/2) + a^2-a = 0 a^2-a-2 = 0 2(0) + b^2-b = 3 b^2-b-3 = 0 Now you can find a and b, and pick the ones that work with the line.
November 6, 2014

Algebra
well, that would be where x^3-x^2+x+1 = x^3+x^2+x-1 2x^2-2 = 0 x = ±1 See http://www.wolframalpha.com/input/?i=solve+x^3-x^2%2Bx%2B1+%3D+%28+x^3%2Bx^2%2Bx-1%29
November 6, 2014

algebra
you have slope=3, so using the point-slope form, the line can be written as y-3 = 3(x-0) or, y = 3x+3
November 6, 2014

Calculus
If v is viewed as a piecewise linear function, then the slopes of the various segments are 154/7 = 21 (374-154)/(17-7) = 22 (418-374)/(19-17) = 22 (770-418)/(35-19) = 22 (1320-770)/(60-35) = 22 (1508-1320)/(64-60) = 47 (3905-1508)/(115-64) = 47 Looks like the 2nd stage kicked ...
November 6, 2014

Intermediate Algebra
If you are talking about powers, 9^(1/2) = 3 x^(1/2) = √x so you are talking about square roots. (-9)^(1/2) is not real, because negative numbers do not have real square roots. That is because if x = √(-9) then x^2 = -9. But all numbers are positive when squared.
November 6, 2014

Algebra help
ok ok v = 243 - 0.2s
November 6, 2014

Physics
Consider m3 to be at (0,0) m1 exerts its force at an angle of 30° m2 exerts its force at an angle of -30° As you say, each force is F=GMm/r^2 The resultant force will be at 0°, with a magnitude of F√3, the sum of the x-components of the two forces.
November 6, 2014

Calculus
y = (3x^2+2√x)/x = 3x + 2/√x y' = 3 - 1/x^3/2 You are correct
November 6, 2014

Trigonometry
secx = 2.1754 x = 0.4776 SInce secx is positive in QI and QIV, the other angle is 2π-0.4776 arcsin(2x) makes no sense, since x is an angle. That's if we are still referring to the first question. Now, in general, if sinθ = 2x, then cosθ = √(1-sin^2&#...
November 6, 2014

Trigonometry
c = 2πr, so one revolution of the plane travels 4π meters So, now we know that 5 min * 60s/min * 0.4rev/s * 4πm/rev = (5*60*4π)/(0.4) = 300π meters
November 6, 2014

Math
There is a good discussion of this problem at http://mathforum.org/library/drmath/view/65003.html This is, of course, a case involving Fermat's Last Theorem.
November 6, 2014

Math- Had Sub teacher, need help
apparently you stopped reading before finishing things. Read on past where it says So, the revenue will be ...
November 6, 2014

Math- Had Sub teacher, need help
revenue = rent * apts if there are x $7 increases, then we have rent = 294+7x units rented = 120-x So, the revenue will be (294+7x)(120-x) = -7x^2 + 546x + 35280 Recall that the vertex of a parabola is at x = -b/2a, which in this case is x = 546/14 = 39 So, with 39 rent ...
November 6, 2014

Algebra
recall that the vertex of a parabola is at x = -b/2a, which in this case is x = 1/.0064 = 156.25 so, just find f(156.25)
November 6, 2014

Math - incomplete
better explain some more about the diagram.
November 6, 2014

Math help!
m=r+4 m-10 = 3(r-10) Miriam is 16 and Ricardo is 12
November 6, 2014

Calculus
in that case, z^2 = (x+3)^2 + (5(x+3)/x)^2 z = (x+3)√(x^2+25) / x dz/dx = (x^3-75) / x^2√(x^2+25) and x = ∛75
November 6, 2014

Calculus
If the foot of the ladder is x feet from the fence, and it reaches to a height h on the wall, then using similar triangles, x/3 = (x+7)/h h = 3(x+7)/x the ladder's length z is z^2 = (x+7)^2 + h^2 = (x+7)^2 + (3(x+7)/x)^2 z = (x+7)√(x^2+9) / x So, for minimum z, we ...
November 6, 2014

CAL
#1 correct #2 is only partially complete f'(x) or df/dx y' or dy/dx
November 6, 2014

CAL
The _____________ of a function is a formula for the slope of the tangent line to that function at any point x. When the function is defined as f(x), the derivative will be written as __________or ________. When the function is written in the form of y =, the derivative is ...
November 6, 2014

Calculus
ohhh.. I think I know what I did wrong.. I did not even realize that I was doing something completely different
November 6, 2014

Calculus
wow - remember the chain rule if u = cos(x^4) then we have y = u^4 y' = 4u^3 u' y' = 4 cos^3(x^4) * (-sin(x^4)(4x^3) = -16x^3 sin(x^4) cos^3(x^4) y = sinx/(1+cos^2(x)) y' = [(cosx)(1+cos^2(x)) - (sinx)(2cosx)(-sinx)]/(1+cos^2(x))^2 y = sinx(sinx+cosx) y' = ...
November 6, 2014

Calculus
Find the derivatives of the following 18. y=〖cos〗^4 x^4 ANSWER: tanx2 19. y= sinx/(1+ 〖cos〗^2 x) ANSWER: 3sinx 20. y=sinx(sinx+cosx) ANSWER: sinx Can you check my answers?
November 6, 2014

Math Help
since loga + logb = log(ab) we have 4(ln(z(z+5)) = ln (z(z+5))^4 2ln(z-5) = ln (z-5)^2 Now, since loga - logb = log(a/b), we have ln ( (z(z+5))^4 / (z-5)^2 )
November 6, 2014

Calculus
Looks good to me. Nice work.
November 6, 2014

Calculus
3G 4H 5F 6B (though I never heard of such a term) 7E 8C 9A 10D Wow - either your order is mixed up, or you have some serious reviewing to do...
November 6, 2014

Calculus URGENT
f(x) = √x f(0) = 0 f(9) = 3 So, the slope of the secant is 1/3 f'(x) = 1 / 2√x So, we want to find c such that 1 / 2√c = 1/3 √c = 3/2 c = 9/4 So, c is in the interval [0,9] just to check, f(9/4) = 3/2 So, the equation of the tangent line at c is y...
November 6, 2014

Algebra 2
192x^2y + 72x^3 = 24x^2(8y+3x) 24rxy - 9rx^2 = 3rx(8y-3x) The only common factor I can see is 3x, so we have 3x(64xy+24x^2-8ry+3rx) Not sure just where you're trying to go with this Now, if the original had been without the parentheses, (192x^2y+72x^3)-24rxy-9rx^2 then we ...
November 6, 2014

matg
20 years is 4 half-lives, so there would be 300 * (1/2)^4
November 6, 2014

Science
PE = mgh = (45)(9.81)(2) J
November 6, 2014

Math
I get z(2.75,0) = 22
November 6, 2014

physics
recall your equation of motion. In this case, the height, as a function of t is h(t) = 2.54t - 4.9t^2 This is just a parabola, with the vertex at t = -b/2a = 2.54/9.8 = 0.26 So, just plug in t=0.26 to find the maximum height, h(0.26)
November 6, 2014

algebra
It's easy to construct such a polynomial with zeroes that are very difficult to find: 3x^5 - 12x^4 + 9x^3 + x^2 - 12 But, if you start out with the roots, it's easy to build the polynomial: (x-3)(2x+5)(3x-7)(x^2+4) = 6x^5 - 17x^4 - 14x^3 + 37x^2 - 152x + 420
November 6, 2014

geometry
draw a line mark point A. mark point B at a distance of 8.5 units away from A. Now, draw a circle of radius 6.2, with center at B. Point C can be anywhere on the circle just drawn.
November 6, 2014

Math
.815 = 815/1000 .021 = 21/1000 So, she added thusly: 5 815/1000 + 6 21/1000 = 11 876/1000 = 11 219/250
November 6, 2014

math
1.2 - (0.75 + 0.125 + 0.09) = 1.2 - 0.965 = 0.235
November 6, 2014

math
recall the slope-intercept form of a line: y = mx+b
November 6, 2014

Object Oriented Programming Concept Using C++
use how? R = 2T?
November 6, 2014

Math
y = x^2+6x+4 = x^2+6x+9 + 4-9 = (x+3)^2 - 5
November 6, 2014

math
For x motors, $150, so each cost 150/x For a cost of 150/x - 5, then there were x+1 motors, all for the same $150: (x+1)(150/x - 5) = 150 x = 5 check: 5 @ $30 = 150 6 @ $25 = 150
November 6, 2014

math
(5+x)/(6+2x) = 3/5
November 6, 2014

math
original price for x radios is 1200/x So, (x-6)(1200/x + 10) = 1200
November 6, 2014

math
look at the multiples of 4 0 4 8 12 16 20 ... You can also consider that since the second number is 1 times the row number, then the row is 4.
November 5, 2014

algebra help please
well, just plug in the value for t: t=5: 2200 + (-480*5) = 2200-2400 = -200 and do the others the same way
November 5, 2014

please help! algebra
clearly there is no constant difference. Check for constant ratio (-12)(-5) = 60 (60)(-5) = -300 ... we have a winner. SO, what is 1500 * -5 ?
November 5, 2014

Trig
well, if you insist on using tan, then note that the base of the slide is √(250^2 - 107^2) = 225.9 cm out from spot directly under the slide's top. So, now we have tan θ = 107/225.9 = 0.47 θ = 25.3°
November 5, 2014

Math, please help
subtract the area of the painting from the total area. If the matte has width w, then (10+2w)(15+2w) - 10*15 = 10*15 4w^2 + 50w - 150 = 0 2(2w-5)(w+15) = 0 w = 5/2 = 2.5
November 5, 2014

Math
no way to tell the perimeter from just the area. All we know is that the smaller dimension is greater than 1.7 m.
November 5, 2014

Help please Math
No, what you want is a(bc) = (ab)c multiplication is associative. It is also distributive over addition: a(b+c) = ab + ac Of course, if a=1, a(bc) = (ab)(ac) because 1(bc) = (1a)(1b) = bc
November 5, 2014

pre-algebra
Nope. It triples every 4 hours, so in 24 hours it has tripled 6 times: x * 3*3*3*3*3*3 = x * 3^6
November 5, 2014

chemistry
since PV=kT, PV/T is a constant. So, using the given numbers, (.14 atm)V/(271+48) = (756 torr)(.295)/(271+18) You will need to reconcile atm and torr, and then solve for the new V
November 5, 2014

Algebra
not much of a scenario. They want a situation in real life which would produce such a decline and then increase in typing speed.
November 5, 2014

geometry - incomplete
how is point G defined?
November 5, 2014

TRIG WORD PROBLEMS
not sure just what you did, but if the height is x, then x/25 = tan 38° Actually, x is the shorter leg. The 38° angle is from the ground to the top of the building.
November 4, 2014

Calculus- Please Help!
Since moles is constant, nR is constant. SO, V dP/dt + P dV/dt = nR dT/dt You now have n = 2*6.02*10^23 P = 5 V = 15 dP/dt = -3 dV/dt = 0.6 So, plug in the numbers and solve for dT/dt
November 4, 2014

English
Thank you
November 4, 2014

English
In the Call of the Wild, Buck did not fight back when Hal was beating, him because? My answer is that he did not have the strengh
November 4, 2014

English
Thsnk you very much.
November 4, 2014

English
The hairy man represents what in the call of the wild? My answer is fear
November 4, 2014

calculus
v = ds/dt = 2/√(1+4t) a = dv/dt = -4/(1+4t)3/2 now just plug in t=6
November 4, 2014

physics-distance
r dθdt = .5 * 6.9 = 3.45 m/s is the linear speed. so, 3.45 m/s * 35*60 s = 7245 m
November 4, 2014

Algebra 2
(5+2w)(12+2w) - 5*12 = 168 Now just solve for w.
November 4, 2014

Algebra
that would be the plan. Should be pretty straightforward. One you get back to (1,1) you're done.
November 4, 2014

math
If there are v,w,x,y bike, trikes, tandems and unicycles, respectively, then we know v = 32 x=y Assuming all riders wear helmets, v+w+2x+y = 57 2v+3w+2x+y = 115 32 bikes 13 trikes 4 tandems 4 unicycles
November 4, 2014

Math
(x-2)^2 can never be negative. It is its minimum value of 0 when x=2. So, the vertex is at x=2. y(2) = -3, so the vertex is at (2,-3)
November 4, 2014

algebra
the slope must be 3, so now you have a point and a slope: y-2 = 3(x-0) y = 3x+2
November 4, 2014

Math Gr 12
OK. Now what? Hint: sin x = 1/1.25 = 0.8
November 4, 2014

math
the numbers are x,x+2,x+4 x + x+2 = (x+4)^2 - 201 Now just expand, collect terms, and solve the quadratic.
November 4, 2014

calculus - unclear
Seems like we need to know something about the production of bandages. Is it continuous? Instant batches of some fixed number? Production over a period of days? Is the consumption to be considered a continuous function? I see no way to solve this with the information given.
November 4, 2014

Calculus please help me
recall your second derivative concave up if f" > 0 inflection when f" = 0 concave down if f" < 0 So, you have f"(x) = 50x(x^2+75)/(x^2-25)^3 f" < 0 on (-∞,-5) f" > 0 on (-5,0) f"(0) = 0 f" < 0 on (0,5) f" > 0...
November 4, 2014

Algebr
just the way you would evaluate any complicated expression. Start deep and work outward: f^-1(5) = 13 f^-1(13) = 2 f^-1(1) = 5 So, you have f^-1((13+2)/5) =f^-1(3) = 1
November 4, 2014

Math
f decreasing means f' < 0 f' = 18x^2 - 126x - 144 = 18(x^2-7x-8) = 18(x+1)(x-8) Since that is a parabola which open upward, f' is negative between the roots. f(x) is decreasing on the interval (-1,8) This can be verified by looking at the graph: http://www....
November 4, 2014

Algebra
f(x) = (x+5)/3 f^-1(x) = 3x-5 g(x) = 1/(f^-1(x)+1) = 1/(3x-4) g(3) = 1/5 Of course, you might also have meant just what you typed, in which case g(x) = 1/f^-1(x) + 1 = 1/(3x-5) + 1 = (3x-4)/(3x-5) and so g(3) would be 5/4
November 4, 2014

maths
I'd say it depends on what is in the bag.
November 4, 2014

Algebra 1 please help answer
you have two conversion factors: $3 = 2 lb 1 apl = 5 oz So, to convert $ to lb, do $9 * 2lb/$3 = 18/3 = 6 lb 6lb * 16oz/lb * 1apl/5oz = 96/5 = 19.2 apples
November 4, 2014

Algebra 1 please help
7 gal * 25mi/gal = 175 mi
November 4, 2014

algebra
If A has a girls and B has b girls, then we are told: a-7 = b a+4 = 2b So, a=18 b=11 That means that A had 17 boys and B had 24 boys
November 4, 2014

Algebra HELP!
x in * 1m/39.37 in = x/39.37 m y = x/39.37
November 4, 2014

Math
#1 solve for x in x(1+.18/4)^(4*5) = 30000 #2 again, x(1+.045/2)^(2*15) = 50000 #3 100*(1/2)^(15/25)
November 4, 2014

geometry
Not sure what you mean by "rows" of wires. If you just need to find the perimeter of the rectangle, that is 2(0.7+0.5) km
November 4, 2014

Calculus
if g(x) = 1/√f(2x) dg/dx = (-1/2)f(2x)^-3/2 * f'(2x) * 2 so, g'(1) = (-1/2)f(2)^-3/2 * f'(2) * 2 = (-1/2)(5^-3/2)(-1)(2) = 1 / 5√5
November 4, 2014

Calculus
#1 f' = 3x^2-8x+5 f" = 6x-8 f is concave up when f" > 0 #2 f' = 6x^2-6x-6 maybe it cannot be factored, but since the discriminant is positive, it has real solutions. Use the quadratic formula to find them. #3 you want the slope to be 3. y' = 2e^x - 3 ...
November 4, 2014

mathematics
(y,z) = (5/2, -13/4)
November 4, 2014

Calculus
f' = 6x^2+9 clearly, f' is always positive, so there are no extrema, and no intervals where f is decreasing. Just think of what you know of the curve y=x^3
November 4, 2014

Calculus
the distance z is found using z^2 = u^2 + v^2 - 2uv cos 2pi/3 what are u and v? The girl's and boy's distances, where u = -6t v = 10t z^2 = 136t^2 - 60t^2 z^2 = 76t^2 so, now you know you have to find z(1/2), and then use z dz/dt = 152 t
November 3, 2014

Math
6*36 + 4*15 = ?
November 3, 2014

Math
48+64 + 2(48+64) = 336
November 3, 2014

Algebra
just evaluate as you would anyu other expression. work your way out from the inside: f^-1(3) = 4 (because they told you that f(4) = 3) So, now you want f^-1(4) That is 7, because f(7) = 4 The final answer is 7.
November 3, 2014

math
you want to spend less than $15 to buy three books. On average, the books must cost less than how much, each?
November 3, 2014

Algebra
f^-1(x) = (x-5)/4 So, f^-1(9) = 1 f^-1(1) = -1 So, no, the answer would be -1.
November 3, 2014

Algebra
No, you can't have h^-1 with both x and y in it. In fact, there are no x's here at all. Just interchange h and y and solve for the new h: y = (1+h)/(2-h) y(2-h) = (1+h) 2y - yh = 1+h h(1+y) = 2y-1 h = (2y-1)/(y+1) So, h^-1(y) = (2y-1)/(y+1) h^-1(5) = 9/6 = 3/2 check: h...
November 3, 2014

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