Thursday

November 26, 2015
Total # Posts: 31,844

**math**

amount of 45% stuff --- x ml amount of 15% stuff ---- 780-x mls .45x + .15(780-x) = .35(780) times 100 to get rid of decimals 45x + 15(780-x) = 35(780) take over from here
*June 1, 2015*

**Math**

your first response tells me you are having difficulties evaluating a function for a given x x = -1 , y = 3(-1)^2 - 5(-1) - 5 = 3+5-5 = 3 so the point is (-1,3) x = 0 , y = -5 , so the point is (0,-5) x = 1 , y = 3(1)^2 -5(1) - 5 = -7 so the point is (1,-7) x = 2 , y = -3 , ...
*June 1, 2015*

**Math**

make a sketch of the graph using x = -1,0,1,2,3
*June 1, 2015*

**Math (check answers)**

correct , see http://www.wolframalpha.com/input/?i=plot+y+%3D+16x+%2B+150%2C+y+%3D+-x%5E2+%2B60x+-+10
*June 1, 2015*

**math**

trust yourself!
*June 1, 2015*

**Linear quadratics and inequalities**

I meant to say: ".. they intersect at a negative x and a value of x which would result in a negative height."
*June 1, 2015*

**Linear quadratics and inequalities**

I graphed your functions using Wolfram and they don't intersect at a negative x and a value of showing which would show a negative height. check your equations, or else the question is bogus http://www.wolframalpha.com/input/?i=plot+y%3D-0.1x%5E2+%2B2.9x%2C+y+%3D+-x%2B10
*June 1, 2015*

**math**

816 is correct, but I am interested to know why you decided on A.
*June 1, 2015*

**math**

amount of dextr... ----- x amount of water ------ 980-x .55x + 0(980-x) = .275(980) .55x = 269.5 x = 490 mls so you need 490 mls of the dextrose and 490 mls of water (notice that 27.5% = (1/2) of 55% )
*June 1, 2015*

**maths**

cos^2 30° cos^2 45° + 4sec^2 60° + (1/2)cos^2 90° - 2tan^2 60° these are all special angles and you should memorize the trig ratios of the 30-60-90 and the 45-45-90 triangles = (√3/2)^2 (1/√2)^2 + 4(2)^2 + (1/2)(0) - 2(√3)^2 = (3/4)(1/2...
*June 1, 2015*

**mathematics**

What's the question? How many kids are in the pool? What is the water temperature? ??
*June 1, 2015*

**Trigonometry**

Did you make your sketch?? If so, then you will see that tan41° = 50/d d = 50/tan41 = ....
*June 1, 2015*

**Math Algebra 1111**

Whatever the domains of F(x) and G(x) are they would be the same for (F+G)(x) but for (F/G)(x) you would have to restrict any values for which G(x) = 0 In effect you stated that with an example
*June 1, 2015*

**Math**

mine: 3x^2 - 15x + 6 = 0 x^2 - 5x + .... = -2 + ..... x^2 - 5x + 25/4 = -2 + 25/4 (x-5/2)^2 = 17/4 (x - 5/2)^2 - 17/4 = 0 suppose I multiply by 3 3(x-5/2)^2 - 51/4 = 0 looks like they were both correct
*June 1, 2015*

**math**

let the original number be 10a + b where a is the tens digit and b is the units digit. New number: 10(a+4) + b-4, where 4 < b < 9 10(a+4) + b-4 = 2(10a + b) 10a + 40 +b-4 = 20a + 2b 10a + b = 36 a = (36-b)/10 the only value of b which would make 36-b a multiple of 10 is ...
*June 1, 2015*

**Math**

sin^-1 x is the angle Ø so that sinØ = x or x/1 so you have a right-angled triangle with opposite side x and hypotenuse 1 then y^2 + x^2 = 1 y = √(1 - x^2) and cos(sin^-1 x) = cosØ = √(1 - x^2) test for some value of x let's say x = .1234 ...
*June 1, 2015*

**Math**

wecome, please stick to one name, switching names makes it hard to go back in replies
*June 1, 2015*

**Math**

RS = 1 + sin^2 x/cos^2 x = (cos^2 x + sin^2 x)/cos^2 x , using common denominator = 1/cos^2 x = sec^2 x = LS
*June 1, 2015*

**Math**

As you can see from Steve's graph, your "critical" values are x = -1,2,3 so you have the following line segments 1. for x ≤ -1 : let x = -2, y = 10 let x = -1 , y = 7 , slope = -3 y-7 = -3(x+1) -----> y = -3x + 4 2. for -1 ≤ x ≤ 2 let x = -1...
*June 1, 2015*

**lotto math equation**

I have no clue what that is supposed to mean.
*June 1, 2015*

**Algebra II**

no, you have to do the division first, even though the devision is not exact. 4² + [15 ÷ 9 - 3(2)] = 16 + [ 5/3 - 6] = 16 + [-13/3] = 35/3 or 11 2/3 http://www.wolframalpha.com/input/?i=4%C2%B2+%2B+%5B15+%C3%B7+9+-+3%282%29%5D+
*May 31, 2015*

**alegra2**

wolves(t) = 1350 (1.1)^t , were t is number of yrs since 2005 wolves(10) = 1350(1.1)^10 = ....
*May 31, 2015*

**alegbra**

value = 34750 (.88)^7 = ...
*May 31, 2015*

**algebra**

length --- x width ---- x height ---- x+5 x(x)(x+5) = 72 x^3 + 5x^2 - 72 = 0 I tried ±2, and ±3 x = 3 works so by synthetic long division x^3 + 5x^2 - 72 = 0 (x-3)(x^2+ 4x + 24) = 0 the quadratic has no real solution, so x = 3 the prism is 3 by 3 by 8
*May 31, 2015*

**Math**

But why not lay the cone in sideways so that the base of the cone rests against the end of the box So the base of the cone fits the 3 cm by 3 cm end and its height is 6 cm radius = 1.5 cm Volume = (1/3)π(1.5)^2 (6) = 4.5π cm^3 (cosine's cone is only 2.25π cm^3)
*May 31, 2015*

**Math**

Your major mistake is in line 4 You are basically saying log(A-B) = logA/logB there is no such relation! From line 3: y=4log2(8x-56)-12 = 4log2(8(x-7)) - 12 = 4log28 + 4log2(x-7) - 12 = 4(3) + 4log2(x-7) - 12 = 4log2(x-7) , where x>7
*May 31, 2015*

**Algebra 1**

Where does the 126 come from? the original question had √136
*May 31, 2015*

**Algebra 1**

short leg --- x longer leg -- x+2 x^2 + (x+2)^2 = (√136)^2 x^2 + x^2 + 4x + 4 = 136 2x^2 + 4x - 132 = 0 x^2 + 2x - 66 = 0 I will complete the square: x^2 + 2x + .... = 66 + ... x^2 + 2x + 1 = 66 + 1 (x+1)^2 = 67 x+1 = ±√67 x = -1 + √67 , since x > 0...
*May 31, 2015*

**precal**

x/r = cosØ ---> x = rcosØ y/r = sinØ ---> y = rsinØ rcosØ = rsinØ sinØ/cosØ = 1 tanØ = 1 Ø = π/2 which makes sense to me, x = y is a straight line with (0,0) as the intercept and a 45° angle &...
*May 31, 2015*

**Maths**

If 4 buns and 4 cakes cost $4 ,then 1 buns and 1 cake costs $1 --> 4b + 4c = 4 b + c = 1 you want 5 buns + 5 cakes = 5b + 5c = 5(b+c) = 5(1) = $5 The fact that 3 buns cost as much as 2 cakes is not needed and is simply a distraction. It would matter only if you needed the ...
*May 31, 2015*

**trignometry(maths)**

done, see previous post
*May 30, 2015*

**maths**

I assume you mean: (4cosØ - sinØ)/(2cosØ+sinØ) = 4/5 the way you typed it, the statement would be false. given: tanØ = 4/3 make a sketch of the right-angled triangle. You should recognize the 3-4-5 right-angled triangle, if not r^2 = 3^2 + 4^...
*May 30, 2015*

**Algebra**

amount invested at 9% --- x amount invested at 5% --- 1900-x .09x + .05(1900-x) = 143 multiply by 100 to get rid of decimals 9x + 5(1900-x) = 14300 take over from here
*May 30, 2015*

**Math help please thank you**

amount needed of the 25% stuff --- x L amount needed of the 50% stuff ---- 500-x L .25x + .50(500-x) = .35(500) times 100 25x + 50(500-x) = 35(500) 25x + 25000 - 50x = 17500 -25x = -7500 x = 300 L state your conclusion
*May 30, 2015*

**Math**

The slopes of perpendicular lines must be negative reciprocals of each other, so... what do you think ?
*May 30, 2015*

**Math**

No idea what you mean by "x's cannot repeat" The definition of a function is found in every textbook that deals with that topic
*May 30, 2015*

**Hanahan**

I would subtract them to get 10y = 80 y = 8 back into the second: 4x + 24 = -40 4x = -64 x = -16
*May 30, 2015*

**linear systems**

To have an infinite number of solutions, both equations are really the same equation if we multiply the first by 3, 2x + 3y = 48 comparing with the 2nd: kx + 3y = 48 there would be an infinite number of solutions if k = 2 One solution, k ≠ 2 to have no solution, the two ...
*May 30, 2015*

**Math**

I assume you mean $10.22 So the rate is 10.22/145.99 = .07 or 7% y = .07x
*May 30, 2015*

**Math word problem**

number of $1 coins --- x number of quarters ---- y x + y = 21 100x + 25y = 1275 --> 4x + y = 51 subtract them: 3x = 30 x = 10 then y = 11 He has 10 dollar coins and 11 quarters check value: 100(10) + 25(11) = 1275 cents = $12.75
*May 30, 2015*

**maths**

I don't understand your notation
*May 30, 2015*

**Math please help!!**

did you make a sketch? let the shorter diagonal be x by the cosine law: x^2 = 78^2 + 90^2 - 2(78)(90)cos35° ... x = 51.8 to the nearest tenth let the longer diagonal by y y^2 = 78^2 + 60^2 - 2(78)(90)cos145° etc
*May 30, 2015*

**maths**

tan70 = tan(90-20) = cot 20 but cot 20° = y then 1 + tan^2 70 = 1 + cot^2 20° = 1 + y^2
*May 30, 2015*

**math**

so he has 63/7000 m^3 and 1 m^3 is 100^3 cm^3 so he has 63/7000 * 1000000 cm^3 or 9000 cm^3 available let the length be h area of cross-section = 12(15) - (10)(12) = 60 cm^2 60h = 9000 h = 150 cm long or 1.5 m
*May 30, 2015*

**math**

first of all: (x - 1/x)^3 = x^3 - 3x + 3/x - 1/x^3 so we will need x^3 if x = 1 - √2, then x^3 = (1-√2)^3 = 7-5√2 , I will leave it up to you to expand it So we have : (7 - 5√2) - 3(1 - √2) + 3/(1 - √2) - 1/(7 - 5√2) rationalize the ...
*May 30, 2015*

**math**

1/(1+√2) + 1/(√2 + √3) + 1/(√3 + √4) rationalize each term: 1/(1+√2) = 1/(1+√2) * (1-√2)/(1-√2) = (1-√2)/-1 = √2 - 1 1/(√2 + √3) = 1/(√2 + √3) *(√2 - √3)/(√2 - √3...
*May 30, 2015*

**math**

x = 1 - √2 , then x^2 = 1 - 2√2 + 2 = 3 - 2√2 then (x - 1/x)^2 = x^2 - 2 + 1/x^2 = 3-2√2 - 2 + 1/(3-2√2) = .... rationalizing 1/(3-2√2) 1/(3-2√2) =1/(3-2√2 * (3+2√2)/(3+2√2) = (3+2√2)/1 so back in ... = 3 - 2&#...
*May 30, 2015*

**Algebra/Math**

"above" ---> greater than temp > -15
*May 29, 2015*

**math**

shorter piece --- x longer piece ---- 3x-2 solve for x: x + 3x-2 = 10 take it from here
*May 29, 2015*

**Maths**

Clearly Steve answered this for you in great detail here http://www.jiskha.com/display.cgi?id=1432801604
*May 29, 2015*

**math**

the centre must be the midpoint of A and B and that midpoint is (1/2 , 5) so the equation must be: (x - 1/2)^2 + (y - 5)^2 = r^2 but (5,7) lies on it, so (5-1/2)^2 + (7-5)^2 = r^2 81/4 + 4 = r^2 r^2 = 97/4 (x - 1/2)^2 + (y - 5)^2 = 97/4 btw, the fact that a diameter subtends a...
*May 29, 2015*

**Mathematics**

time = distance/rate blue car's time = 150/25 = 6 hrs red car's time = 150/60 = 2.5 hrs so, since the blue car left at 9:30 am, it will arrive 6 hours later , at 3:30 pm the red car left at noon, so will arrive 2.5 hours later, at 2:30 pm Why would you need to ...
*May 29, 2015*

**college geometry**

"college" geometry? Why not just plot the 3 given points and then count to find what the 4th point has to be?
*May 29, 2015*

**college geometry**

let B be (x,y) then (x+1.7)/2 = 2.1 x+1.7 = 4.2 x = 2.5 find y in the same way, and you have B
*May 29, 2015*

**Math**

prob = (2/12)(1/11) = 1/66
*May 28, 2015*

**math**

I will interpret "There is an east wind blowing at 60 mph" as the wind is blowing from the east. anyway, ... we just have a right-angled triangle so that x^2 = 480^ + 60^2 solve for x
*May 28, 2015*

**college geometry**

for any point (a,b) , the image of (a,b) with symmetry with respect to the origin would yield the point (-a,-b) so for (3,4) ----> (-3,-4) I will let you do the others.
*May 28, 2015*

**Math**

complete the square .... y = 3(x^2 - 6x ....) + 4 = 3(x^2 - 6x + 9 - 9) + 4 = 3( (x-3)^2 - 9) + 4 = 3(x-3)^2 - 27 + 4 = 3(x-3)^2 - 23 I trust you can take it from here.
*May 28, 2015*

**Math**

I am an avid camper and have never seen a sleeping bag like that, ..... I will give you an example of the given shape of the sleeping big with points on the x-y plane let AB, with points A(0,12) and B(0,-12) be the zipper side let CD with C(6,-8) and D(6,8) be the side ...
*May 28, 2015*

**@ Person helping**

Unless you know what you are doing, it doesn't help to answer questions for other students incorrectly. your line of : 3.14*1.4*2*9=79.128 2*3.14*1.4*1.4=3.5168 79.128+3.5168=82.6448 is total mathematical gibberish.
*May 28, 2015*

**math**

Volume = π r^2 h = π(1.4)^2 (9) = appr 55.418 m^3 = appr 554000 L, rounded to the nearest thousand litres.
*May 28, 2015*

**Math**

Just "translate" 5/6 as many vans as trucks vans = (5/6)trucks or 6vans = 5trucks Suppose there are 18 trucks, then the number of vans = (5/6)(18) = 15 what is 15/18 ?
*May 28, 2015*

**trig**

As Steve pointed out, you answer makes no sense, nor can I understand what your calculations are supposed to represent. It almost looks like you are assuming there is a right-angled triangle. There isn't one. If you make a sketch for the problem you would see that this is ...
*May 28, 2015*

**college geometry**

or, you can notice that they lie on the same horizontal line, so (b,3) is either 3.5 units to the right or to the left of (7,3) so b = 7 ± 3.5 which is what Steve shows in his last line as well.
*May 27, 2015*

**math**

Dan ---- x Sarah ---(2/5)x Chris --- (6/5)x x + 2x/5 + 6x/5 = 6 times 5 5x + 2x + 6x = 30 13x = 30 x = 30/13 ft Sarah --- (2/5)(30/13) = 12/13 (chris has (6/5)(30/13)= 36/13 check: 30/13 +12/13 + 36/13 = 78/13 = 6 my answer is correct
*May 27, 2015*

**Math**

LS = (sin^2 Ø/(sin^2 Ø cos^2 Ø) - 1 = (sin^2 Ø/(sin^2 Ø cos^2 Ø - (sin^2 Ø cos^2 Ø)/(sin^2 Ø cos^2 Ø) = (sin^2 Ø - sin^2 Ø cos^2 Ø)/(sin^2 Ø cos^2 Ø) = sin^2 Ø (1 - ...
*May 27, 2015*

**Algebra 2**

The question makes no sense. There are an infinite number of points which are not part of the solution. Here is what the graph looks like http://www.wolframalpha.com/input/?i=plot+y+%3C+%E2%80%93%7Cx+%E2%80%93+4%7C
*May 27, 2015*

**Calculus**

f(x)=(1-x)/(1+x) and g(x)=x/(1-x) f(g(x)) = f(x/(1-x) ) = [ 1 - x/(1-x)] / [1 + x/(1-x)] multiply top and bottom by 1-x = (1-x - x) / (1 - x + x) = (1 - 2x)/1 = 1 - 2x check: pick an unlikely x value and using my calculator g(2.35) = -1.7407... f(-1.7407) = -3.699999 or -3.7 ...
*May 27, 2015*

**Math**

My equation was : x^2 = 2y + 1 (Yours in not even an equation.) manipulating this: y = (1/2)(x^2) - 1/2 from this I can read that the vertex is (0,-1/2) which is true according to the focus - directrix property in that the vertex is midway between the focus and the directrix. ...
*May 27, 2015*

**math**

sketch the sector to the right of the vertical. Label the centre as C, the end of the swing as A and the point on the horizontal hitting the pendulum B So AB = 15 cm we can find OA tan 35° = 15/OA OA = 15/tan35 = 21.422... so the length of the pendulum is 21.422 + 5.3 = 26...
*May 27, 2015*

**Math**

made a Venn diagram, labeled the intersection of the soccer circle and the tennis circle as x then ... 13-x + x - 8-x + 2 = 20 -x = -3 x = 3 All can now be seen from the Venn diagram soccer of tennis --- 18 both soccer and tennis -- 3 only soccer --- 10
*May 27, 2015*

**Geometry - help please**

Can't see the diagram, but this looks like a very common question I have seen many times, so OB^2 + 6^2 = 11.7^2 OB^2 = 100.89 OB = appr 10.0
*May 27, 2015*

**pre-algebra NEED HELP!**

#1, 4,5 are correct #3 SA of a sphere = 4π r^2 so if r = 4 SA = 4π(16) = appr 201 #2, can't see the diagram, will assume r = 8, height = 12 , cover the top but not the bottom SA = πr^2 + 2πrh = π(64) + 2π(8)(12) = appr 804
*May 27, 2015*

**Geomery**

correct (what is that jibberish at the end of your first post ? )
*May 27, 2015*

**Math**

well, 5 x 20 = 100 and 100 x 18 = 1800
*May 27, 2015*

**precal**

x = 3 + 6cost 6cost = x-3 cost = (x-3)/6 similarly , from the 2nd equation sint = (y-6)/6 but we know, sin^2 t + cos^2 t = 1 ( (y-6)/6)^2 + ( (x-3)/6)^2 = 1 (x-3)^2 /36 + (y-6)^2/36 = 1 (x-3)^2 + (y-6)^2 = 36 you should recognize that as a circle with radius of 6 and centre (3,6)
*May 27, 2015*

**Math**

Here is how I would have expected my students to show the steps: subtract the first equation from the second : 7x-3y=43 5x - 3y = 35 2x = 8 x = 4 sub that back into 5x-3y=35 20-3y=35 -3y = 15 y = -5 So the first two lines intersect at (4,-5) But the third line of 4x-ay=61 also...
*May 27, 2015*

**Math**

let the time taken by Jesse be x hrs then the time taken by Leah is 2x hrs then Jesse's rate is 1/x jobs/hr and Leah's rate is 1/2x jobs/hr combined rate = 1/x + 1/2x = (3/(2x)) but 1/(3/2x) = 4 1 = 4(3/2x) 2x = 12 x = 6 It would take Jesse 6 hrs to do the job alone, ...
*May 26, 2015*

**Math**

amount invested at 6% --- x amount invested at 4.5% --- 1200-x .045(1200-x) - .06x = 12 54 - .045x - .06x = 12 -.105x = -42 x = 400 so $400 at 6% and $800 at 4.5%
*May 26, 2015*

**Math help**

done,
*May 26, 2015*

**Math**

The sides for the 30-60-90° triangle could be 1, √3, and 2 so the perimeter = 1 + √3 + 2 = 3 + √3 so get the hypotenuse from 2 to 9 implies each side was multiplied by 4.5 so the perimeter of your triangle = 4.5(3 + √3) = 13.5 + 4.5√3 or appr ...
*May 26, 2015*

**Math**

translate the English into Math... "The sixth term of an A.P. is 5 times the first term" ---> a+ 5d = 5a or 5d = 4a a = 5d/4 "eleventh term exceeds twice the fifth term by 3" term(11) -2 term(5) = 3 a + 10d - 2(a + 4d) = 3 -a + 2d = 3 -5d/4 + 2d = 3 ...
*May 26, 2015*

**math**

draw a Venn diagram, fill in the given data and all mysteries will become clear to you
*May 26, 2015*

**Precalculus**

Surely, you meant: "...in a circle of radius 10 feet... " arc = rØ, where Ø is in radians so convert 35° to radians and plug in or , use a ratio 35°/360° = arc/circumference etc
*May 26, 2015*

**Precalculus**

Tell me where you are running into problems with this basic trig problem. To be successful in studying this topic your MUST be able to do this question.
*May 26, 2015*

**Precalculus**

Did you make your sketch? I will assume you want the height of the streetlamp? then tan30° = height/25 continue ....
*May 26, 2015*

**Trigonometry**

Your x-coordinate of the given point contains a non-readable character, is it (√12,5) ? If so, then tanØ = 5/√12 If it is something else, then tanØ is simply y/x
*May 26, 2015*

**Calculus**

umhh, We don't 'calculate' 5*(t-10)(t-20)=5500 we "solve" 5*(t-10)(t-20)=5500 and I believe I just did that for you.
*May 26, 2015*

**Calculus**

set 5(t-10)(t-20)+4500 = 10000 5(t-10)(t-20) = 5500 (t-10)(t-20) = 1100 t^2 - 30t + 200 = 1100 t^2 - 30 t = 900 I will complete the square.. t^2 - 30t + 225 = 1125 (t-15)^2 = 1125 t - 15 = ±√1125 = ±15√5 t = 15 ± 15√5 , but more than ...
*May 26, 2015*

**math**

mystery math!
*May 26, 2015*

**algebra**

Huh? You said g(x) = 5 which has no variables, and is always equal to 5 so g(-4) = 5 and g(-345) = 5, g(3.432) = 5 g(√89) = 5 , etc g by itself is meaningless, you cannot treat it as a variable and solve for it like you did, it is part of the notation g(...) and means: ...
*May 26, 2015*

**Trigonometry**

for any complex number a + bi the modulus is |√(a^2 + b^2) | and the argument is the angle Ø such that tanØ = b/a I will do the 2nd, you do the rest √3 + i or √3 + 1i or (√3,1) in the Argand plane the modulus is √(3+1) = 2 tanØ...
*May 26, 2015*

**Math**

Yes
*May 25, 2015*

**Algebra**

You don't have to use your real name, but stick to whatever name you pick
*May 25, 2015*

**Algebra**

Why are you switching names ? let sales be x .03x = 180 divide both sides by .03 x = 180/.03 = 6000
*May 25, 2015*

**algebra**

what percent of 8x is 5x? ---> 5x/(8x) * 100% , the x's cancel = (5/8)(100)% = 62.5% 65% of 80x = .65(80)x = 52x Don't make things more difficult than they are
*May 25, 2015*

**Trigonometry**

(cos(2pi)/7)+ i sin((2pi)/7))^5 = 1^5(cos (10π/7) + i sin(10π/7) = (cos (-4π/7) + i sin(-4π/7) , after subtracting 2π from the angle = (cos (4π/7) - i sin(4π/7) )
*May 25, 2015*

**algbra 1**

s + g = 58 4s + 2g = 150 or 2s + g = 75 subtract them: s = 17 then g = 41 there are 17 sheep and 41 geese
*May 25, 2015*

**math**

i = .012/4 , (compounded quarterly) = .003 n = 4 amount = 4000(1.003)^4 = 4048.22 interest earned = $48.22
*May 25, 2015*

**Algebra**

(12y/13)(11/24) = 11y/26
*May 25, 2015*