Monday

January 26, 2015

January 26, 2015

Total # Posts: 28,370

**Calculus**

e^e^2 is a constant. Fix the typo and try again. f is increasing when f' > 0 f is concave up when f" > 0
*December 5, 2014*

**Algebra 2/Trigonometry**

f(x) has 3 sign changes, so 3 or 1 positive roots f(-x) has no sign changes, so no negative roots There might be two complex roots.
*December 5, 2014*

**Calculus**

I think we can assume arccos. If so, then recall that d/dx (arccos(u)) = -1/√(1-u^2) du/dx Now just plug and chug.
*December 5, 2014*

**Calculus**

and you would be wrong. You have it exactly backwards. f is increasing where f' > 0. Better double-check your derivative.
*December 5, 2014*

**Calculus**

If f = √u, f' = u' / 2√u. You have u=3x, so f'(x) = 3 / 2√(3x) f'(3) = 3 / 2√9 = 1/2
*December 5, 2014*

**Intermediate Algebra**

√(40x^3) = √(4x^2)√(10x) = 2x√(10x) √(3/4) * √(4/7) = √(3*4 / 4*7) = √(3/7) √6 + √20 = √6 + 2√5
*December 5, 2014*

**Algebra 1**

What equation has a graph parallel to the graph of 9x + 3y = -22? 1- y = 3x -22 2- y = -3x + 8 3- y = 1/3 x + 12 4- y = - 1/3 x - 2
*December 5, 2014*

**maths**

Don't give much away on the line and point, do you? For the other, just draw a 3-circle Venn diagram, and start filling in the pieces.
*December 5, 2014*

**Math**

Good idea, but you don't need x. There are n sides and n angles. Since you already have 4 angles, there are n-4 remaining. So, (n-2)180 = 125+220+40+295+20(n-4) n=6
*December 5, 2014*

**Math**

Doesn't matter. I'm full!
*December 5, 2014*

**math**

(2/3)/3 * 36 = 2/9 * 36 = 8
*December 5, 2014*

**Algebra**

height=39 length = height+21 = 39+21 = 60
*December 5, 2014*

**Algebra**

review your equation of motion. the distance is s = 1/2 at^2 You know s=435 and a=-9.8 So, just find t.
*December 5, 2014*

**Math**

If he borrowed $x from his friend at 8%, then the rest (170000-x) is at 4%. So, now you have .08x + .04(170000-x) = 9800 x = 75,000
*December 5, 2014*

**Calculus**

The graphs intersect at (-4,20) and (5,25) So, consider the area as a bunch of thin strips, each of width dx, and height equal to the distance between the curves. The area is thus ∫[-4,5] (x+20)-x^2 dx = 1/2 x^2 + 20x - 1/3 x^3 [-4,5] = 243/2
*December 5, 2014*

**Math**

Grrr! It's pi, not pie! ∫[0,π/2] cos^2(3x) dx Now, you know that cos(2u) = 2cos^2(u)-1, so cos^2(u) = (1+cos(2u))/2 and the integral becomes ∫[0,π/2] (1+cos6x)/2 dx = x/2 + 1/12 sin6x [0,π/2] = π/4
*December 5, 2014*

**math**

40:blue = 8:9 blue = 45
*December 5, 2014*

**math Subtraction equation**

x - 25 = 45
*December 4, 2014*

**algebra**

if the given zeros are a,b,c,... then the polynomial is y = (x-a)(x-b)(x-c)...
*December 4, 2014*

**Math**

If x,y,z are all positive, then the sum is 1+1+1+1 = 4 If any are negative, then u/|u| becomes -1, and the total is less. I guess you can list the possibilities, eh?
*December 4, 2014*

**math**

If you mean (32x^3y^4)/(24x^3y^2) * (3x)/(9y) multiply top and bottom to get (96x^4y^4)/(216x^3y^3) = (24x^3y^3)(4xy) / (24x^3y^3)(9) = 4xy/9 Or, you could simplify each fraction first, getting (8x^3y^2)(4y^2) / (8x^3y^2)(3) * (3)(x)/(3)(3y) = 4y^2/3 * x/3y = 4xy/9
*December 4, 2014*

**Math**

I will underline instead of overlining. 0.3 = 0.3333333333333333 It is clear that If both numbers are the same, there is no difference. Otherwise, there is a difference. 3.3 = 3.333333333... 3.34 = 3.3434343434343434... Surely your text has explanations and examples of this ...
*December 4, 2014*

**NEED Math HELP please!!!**

8x - 4xy = 3 8x-3 = 4xy (8x-3)/4x = y -2x-5y = 10 5y = -2x-10 y = -(2x+10)/5
*December 4, 2014*

**Math**

If you go x miles, then you want 1.00 + 0.20(6(x-1)) = 5.00
*December 4, 2014*

**Algebra My bad**

Dr Bob, you are correct. I solved it correctly earlier, and got impatient when it popped up again. My bad.
*December 4, 2014*

**Algebra B PLEASE HELP**

15000(1+r)^2 = 16099.44 r = 0.36
*December 4, 2014*

**pre-calculus**

just for readability, suppose u = cosx Then you have 6u^2-5u-6=0 (3u+2)(2u-3) that means cosx = -2/3 cosx = 3/2 I guess you can take it from there, ok?
*December 4, 2014*

**Math**

If x>=3, |x-3| = x-3 |3-x| = x-3 So, 2x-6 = 1 2x = 7 x = 7/2 If x < 3, |x-3| = 3-x |3-x| = 3-x So, 6-2x = 1 2x = 5 x = 5/2 In either case, |x-3| and |3-x| are the distance of x from 3. Twice that distance = 1, so x is 1/2 away from 3, in either direction.
*December 4, 2014*

**Math**

3√(3-x) = -3/2 √(3-x) = -1/2 3-x = 1/4 x = 11/4 But, that does not fit the original equation. Maybe you meant ∛(3-x) = -3/2 3-x = -27/8 x = 51/8
*December 4, 2014*

**Algebra B**

15000(1+r)^2 = 16099.44 (1+r)^2 = 1.073296 1+r = 1.036 r = 0.036 So, the rate is 3.6%
*December 4, 2014*

**Calculus**

First, it's pi, not pie!!! e/x^4? That's very unusual. As written, it's e/x^4 + π^2/√x I doubt that's what you meant, so try again, and maybe include some parentheses, ok?
*December 4, 2014*

**Math**

max height when t = -b/2a. That is, when t=2 Solve for t when h=0 to find when it hits the ground. So, where is the ball when t=0? That is, where does it start?
*December 4, 2014*

**Calculus**

y = 6x^6 + 4x^13 - 9x^7 + 3 for large x, it's just 4x^13
*December 4, 2014*

**college algebra**

I assume we're doing a G.P. here. a12 = a1*r^11 = 5*(-2)^11 = ?
*December 4, 2014*

**Math calculous**

There's no guarantee that a single parabola will pass through all four points. So, let's pick the fitrst three and see what happens. If y = ax^2+bx+c, then a+b+c = 7 4a+2b+c = 20 9a+3b+c = 43 3a+b = 13 5a+b = 23 2a = 10 a = 5 b = -2 c = 4 y = 5x^2-2x+4 Luckily, (4,76) ...
*December 4, 2014*

**math**

f(-3) = 3^6 - 2*3^4 - 81*3^2 + 162
*December 4, 2014*

**Math**

for x-intercept, solve for x when y=0 for y-intercept, solve for y when x=0
*December 4, 2014*

**Math**

Does each person buy just one cookie? if so, then the profit y on a month of 4 weeks is y = 2*30*4 - 100 For x people per week, that would be y = 8x-100
*December 4, 2014*

**Calculus**

P'(x) = 60x^3 + 30x^2 So, P(x) = 15x^4 + 10x^3 + c If you meant the profit is -50 when no cheese is sold, then P(0) = -50, and c=50. So, P(x) = 15x^4 + 10x^3 - 50 Now plug in x=3 to find P when 300 lbs are sold.
*December 4, 2014*

**Math**

the perimeters are also in the ratio of 2:7 So, find the perimeter of the smaller triangle, and multiply it by 7/2
*December 4, 2014*

**Math**

check to see whether there is a constant term. If not, meaning that the function is just a multiple of x, then it's direct variation.
*December 4, 2014*

**Math**

a car rental costs a daily fee of $20 plus 10 cents per mile. A driver starts from 100 miles away and drives at 20 mph. How far away is he after x hours? You need a constant term and a term with x. For a direct variation, there is no constant term.
*December 4, 2014*

**Math**

3^5 = (3)(3)(3)(3)(3) = 243
*December 4, 2014*

**Math**

Draw your triangle x = -3 y = 1 r = √10 Now use the definitions of the trig functions to fill in the table.
*December 4, 2014*

**Math Question**

it's clear you are in QII, since y>0 and x<0. So, draw your triangle. The hypotenuse is √2, so now you can fill in the table.
*December 4, 2014*

**Simple math**

state: .8/2.69 = 0.297 = 29.7% federal: .18/2.69 = ?
*December 4, 2014*

**Math**

What, your keyboard doesn't have || characters? If x<5, x-5 < 0 So, |x-5| = -(x-5) = 5-x 5x - (5-x) = 6x-5
*December 4, 2014*

**algebra**

However, if you want a polynomial with real coefficients, you need another zero: the conjugate of 1-i = 1+i SO, your polynomial is then (x-(1-i))(x-(1+i))(x-2) ((x-1)+i)((x-1)-i)(x-2) ((x-1)^2+1)(x-2) (x^2-2x+2)(x-2) ...
*December 4, 2014*

**Math**

x^2+4x = x(x+4) 2x^2+13x+15 = (2x+3)(x+5) x^2-16 = (x+4)(x-4) So, you have x(x+4) (x+5) -------------------- (2x+3)(x+5)(x+4)(x-4) Unless there's a typo, the answer is (e)
*December 4, 2014*

**Math**

You started out wanting to simplify y=-15/20.25(x+1.5)^2+0 y=a(x+2)^2+1.5 I assume that means y = -15/20.25 (x+1.5)^2 -15/20.5 (x^2+3x+2.25) = -0.73x^2 - 2.20x - 1.65 Not sure that's any simpler than what you started out with. As for the second, you cannot find a value for...
*December 4, 2014*

**Algebra 1**

The population of a city increases by 4,000 people each year. In 2025 the population is projected to be 450,000 people,. What is the equation that gives the city's population p ( in thousands of people) x years after 2010?
*December 4, 2014*

**math**

√45 = √(9*5) = √9*√5 = 3√5
*December 4, 2014*

**Algebra 1**

I think the answer would be y - 3 = 3/5 (X+6)
*December 4, 2014*

**Algebra 1**

What equation represents the line that passes through the points (6,-3)and (-4,-9)?
*December 4, 2014*

**Algebra 1**

I think the answer would be (3,-4)
*December 4, 2014*

**Algebra 1**

Sorry The possible answers are 1- (-4,-5) 2- (-5,-4) 3- (3,-4) 4- (-3,4)
*December 4, 2014*

**Algebra 1**

Which point is located on the line represented by the equation y + 4 = -5(x-3)?
*December 4, 2014*

**Math**

the other side is 96/12 = 8 So, now you know both sides, and can easily figure the perimeter...
*December 4, 2014*

**Math**

using similar triangles, it is clear that if the tree is halfway to the stake, then it is half as tall as the building. Assuming that the rope touches the top of the tree, that is.
*December 4, 2014*

**Math**

h(t) = 75 + 80/√2 t - 16t^2 h=0 when t=4.563 The horizontal speed is a constant 80/√2 = 56.57 ft/s So, the ball travels 258.12 ft Hmm. We differ slightly. What did you do? And of course, check my math.
*December 4, 2014*

**GEOMETRY**

the area grows as the square of the radius. So, the radius grows as the square root of the area. Since areaB/areaA = 25, radiusB/radiusA = √25 = 5
*December 4, 2014*

**algebra**

domain: all real numbers except holes and vertical asymptotes vertical asymptotes where the denominator is zero and the numerator is not zero holes where the denominator and numerator are both zero horizontal asymptotes at the x-extremes. When x gets huge, you basically have f...
*December 4, 2014*

**Coll Algebra**

since time = distance/speed, we have d/(5-1) = d/(5+1) + 2 d = 24
*December 4, 2014*

**5th grade math**

Just do regular long division. In the quotient, place the decimal point directly above where it is in the dividend. Then move it to the right the number of decimal places as there are in the divisor. In normal long division with integers, the decimal point is at the right end ...
*December 4, 2014*

**math**

well, there are only a few perfect squares: 16 25 36 49 64 100 121 144 169 196 So, check the next numbers for primality. 17 is prime 26 is not and so on
*December 4, 2014*

**Algebra 1**

the slope is 2, so use the point-slope form to get y+3 = 2(x-1) or y-1 = 2(x-3)
*December 4, 2014*

**Algebra 1**

What is an equation in slope-intercept form for the line that passes through the point (1,-3) and (3,1)
*December 4, 2014*

**chemistry**

find the atomic wt of Ca figure the mol wt of CaCO3 So, the mass of Ca is just wt(Ca)/wt(CaCO3) * 1.229g
*December 4, 2014*

**Chemiry 11**

figure how many moles. Then, each mole contains Avogadro's Number of sulfur atoms.
*December 4, 2014*

**Algebra 1**

y = -2x so, k = -2
*December 4, 2014*

**Algebra 1**

For the equation -4y =8x, what is the constant of variation?
*December 4, 2014*

**math**

the given line has slope 5 So, you want a line with slope -1/5 That line is thus (recall the point-slope form): y-3 = -1/5 (x+10) and you can massage that into whatever form you like.
*December 4, 2014*

**Calculus**

I suspect a typo. Why write "1 sqrt(t)"?
*December 4, 2014*

**Algebra**

the distance s = 1/2 at^2 You have s and a, so just find t.
*December 4, 2014*

**Algebra 1**

thank you
*December 4, 2014*

**Algebra 1**

Suppose y varies directly with x and y = 24 when x =8. What is the value of y when x = 10?
*December 4, 2014*

**algebra**

The vertices involving y>=x are clearly (-2,-2) and (3,3) The rest you can surely find... What did you try? See the solutions at http://www.wolframalpha.com/input/?i=solve+x+%E2%89%A5+%E2%88%922%2C+x+%E2%89%A4+3%2C+y+%E2%89%A4+5%2C+y+%E2%89%A5+x+
*December 4, 2014*

**math**

what, no calculator? .01 is around 1/100, so the answer should be somewhere near 3 or 4
*December 3, 2014*

**Math Help**

The increase is 20 20/50 = 40% (of 50)
*December 3, 2014*

**Math**

Since √5 = 5^(1/2), log √5 = 1/2 log5 Not sure what all the other mumbo jumbo means.
*December 3, 2014*

**Math**

√(2-3x) = 9 2-3x = 81 3x = -79 x = -79/3 Remember: (a-bx)^2 is NOT NOT a^2 - b^2x^2 Not that that matters here, anyway, since √(stuff)^2 is just stuff, whatever stuff you have. (√x)^2 = √(x^2) = x. There is no reason at all to square what's inside ...
*December 3, 2014*

**math**

assuming the x side is parallel to the wall, then 2x+4y = 120 The area is 2xy = 2x(120-2x)/4 = 60x - x^2 The maximum area is thus where x=30 As usual with such problems, the maximum area is achieved when the fencing is divided equally among lengths and widths.
*December 3, 2014*

**Algebra 1**

What is an equation in slope-intercept form for the line that passes through the points (1,-3(), (3,1)?
*December 3, 2014*

**Algebra 1**

Thank you trying to help my grandson with his homework
*December 3, 2014*

**Algebra 1**

What is an equation for the line with slope 2/3 and y intercept 9?
*December 3, 2014*

**Algebra 1**

Suppose y varies directly with x and y = 24 when x =8. What is the value of y when x = 10?
*December 3, 2014*

**Algebra 1**

For the equation -4y =8x, what is the constant of variation?
*December 3, 2014*

**Algebra 1**

What is the slope of the line that runs through points (1,1), (0,3)?
*December 3, 2014*

**Pre-Calc/Trig...**

Since An/An-1 = r (1/An)/(1/An-1) = An-1/An = 1/r so, the ratio between terms is still constant.
*December 3, 2014*

**College Algebra**

If the amounts are x,y,z then we have x+y+z = 14000 .03x + .04y + .05z = 539 z = 3y Now just solve for x
*December 3, 2014*

**Algebra 1**

thank you
*December 3, 2014*

**Algebra 1**

the point 12,9 is included in a direct variation. what is the constant of variation
*December 3, 2014*

**Algebra 1**

Thank you, I'm a grandfather trying to help my grandson.
*December 3, 2014*

**Algebra 1**

suppose y varies directly with x and y = 14 when x = -4 what is the value of y when x = -6
*December 3, 2014*

**Algebra 1**

The ordered pairs 1,4 - 2,16 - 3,64 - 4,256 - 5, 1024 represents a function. What rule represents this function. 1- 4 x power 2- 4x 3- xto the 4th power 4- x+4 my answer is 4x
*December 3, 2014*

**trig**

zero. Why? try drawing the triangle...
*December 3, 2014*

**mathematics**

If you mean 2 2/4, that's 10/4 1/4 / 1/4 = 10 yet, who actually writes 2 2/4 instead of 2 1/2? I suspect a typo. And lose the \\\'s. Try /// for fractions.
*December 3, 2014*

**algebra**

w*4w = 392 That gives you w. Now, you want p = 2(w + 4w)
*December 3, 2014*

**AP CALC. AB**

clearly the tangent is horizontal when x^2-2 = 0 h"(x) = (x^2+2)/x^2 And you know that f(x) is concave up when f"(x) > 0 See that graph at http://www.wolframalpha.com/input/?i=integral+x+-+2%2Fx
*December 2, 2014*

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