Saturday

December 3, 2016
Total # Posts: 36,897

**calculus need help studying now**

a) I suggest expanding this rather than using the product rule y = (x^2 - 4x + 4)(x-7) = x^3 - 11x^2 +32x - 28 y ' = 3x^2 - 22x +32 y '' = 6x - 22 = 0 for a point of inflection x = 22/6 = 11/3 <------ there is your error y = (11/3-2)^2 (11/3-7) = (25/9)(-10/3...

*November 28, 2016*

**Math Question**

x^2+y^2-7x=12-4y x^2 - 7x + 49/4 + y^2 + 4y + 4 = 12 + 49/4 + 4 (x - 7/2)^2 + (y+2)^2 = 113/4 = ?113/2 you had that so the centre is (7/2 , -2) and the radius is ?113/2 which is appr 5.315 set you compass at appr 5.3 units, and with the above centre, draw your circle

*November 28, 2016*

**Math**

looks like you are just dividing your input by 10 y = x/10

*November 28, 2016*

**math**

Usually the "length" of a rectangle is greater than its "width", but anyway..... let the length be x yds then the width is x+15 yds x(x+15) = 100 x^2 + 15x - 100 = 0 (x - 5)(x + 20) = 0 x = 5 or x = -20, the latter is not possible the length is 5 and the ...

*November 28, 2016*

**Math (please check my answer)**

2 angles and the contained side of one triangle are the same as 2 angles and the same contained side of another, so ASA makes them congruent.

*November 28, 2016*

**MATH @Damon @ms. Sue**

The assumption we have to make is that the velocity is a linear function of the time .... So we have two ordered pairs (3,53) and (6,62) slope = (62-53)/(6-3) = 3 using the point (3,53) v-53 = 3(t-3) v-53 = 3t - 9 3t - v = - 44 or y = 3t + 44 should be easy to plot for 3 < ...

*November 28, 2016*

**Math**

younger brother --- x years Martha ----------- 2x years x + 2x = 36 carry on

*November 28, 2016*

**Math**

speed of current ---- x mph distance traveled each way ---- d miles time with the current = d/(6+x) time against the current = d/(6-x) d/(6-x) = 2d/(6+x) divide by d 1/(6-x) = 2(6+x) 6+x = 12 - 2x 3x = 6 x = 2 state your conclusion.

*November 28, 2016*

**Math**

salmon's rate of swimming --- x mph let rate of current be y mph 15/(x+y) = 3 3x+3y=15 ---> x+y=5 15/(x-y)=5 5x - 5y = 15 ----> x - y = 3 add those two equations: 2x = 8 x = 4 , then y = 1 state your conclusion

*November 28, 2016*

**algebra**

typo error in 90 c + 180 + 130 c = 4 c^2 + 80 c should be : 90 c + 1800 + 130 c = 4 c^2 + 80 c ---> c^2 - 35c - 450 = 0 (c - 45)(c + 10) = 0 c = 45 or a negative city speed was 45 mph

*November 27, 2016*

**YT host subscribe now!!**

Bro subscribe to the alex jones channel my man!

*November 27, 2016*

**Business Math**

i = .06/12 = .005 n = 20(12) = 240 PV = 50,000 paym = ?? paym( 1 - 1.005^-240)/.005 = 50,000 payment = $358.22 after 7 years: balance of mortgage = 50000(1.005)^84 - 358.22(1.005^84 - 1)/.005 = $38,737.12 Since the current value is 90,000 but they still owe 38,737.12 the ...

*November 27, 2016*

**Math**

"Determine the initial amount of the substance to the nearest 10th of an hour" HUH, since when is an amount of something measured in units of time?? (I will just ignore that part of the question) N = 8 e^(-6t) initial --- t=0 N = 8 e^0 = 8 mg <----- the initial ...

*November 27, 2016*

**Math**

let each of the equal sides be x cm A = (1/2)x^2 dA/dt = x dx/dt we know dA/dx = -5 cm^2 /s dx/dt = -5/x H^2 = x^2 + x^2 = 2x^2 H = ?2 x dH/dt = ?2 dx/dt = ?2(-5/x) so when x = 10 dH/dt = -5?2 /10 = -(1/2)?2 cm/s or appr -.707 cm/s

*November 27, 2016*

**Algebra**

number of dimes ---- x number of nickels ---- 2x + 1 value of coins: 10x + 5(2x+1) = 165 10x + 10x + 5 = 165 take over

*November 27, 2016*

**math**

http://www.jiskha.com/display.cgi?id=1480267024

*November 27, 2016*

**Math**

the way you typed it .... -5 + ?-50/10 = -5 + 5?2 i/10 = -5 + (?2/2) i what you probably meant: (-5 + ?-50)/10 = (-5 + 5?2 i)/10 = -1/2 + (?2/2) i

*November 27, 2016*

**Emma**

We solve equations, you don't have an equation if you meant: evaluate (?6+i)(?6-1) = 6 - ?6 + ?6i - i I have a strong feeling you meant: (?6+i)(?6-i) = 6 - i^2 , but i^2 = -1 = 6+1 = 7

*November 27, 2016*

**Algebra**

y = kx given: x=3, y=10 10 = k(3) k = 10/3 so y = (10/3)x when x = 6 y = (10/3)(6) = 20

*November 27, 2016*

**precalcalculus**

I assume you are familiar with the tradional way of identifying the information given about a triangle, such as ASA, SAS, SSS and SSA use "cosine law" for SAS and SSS use "sine law" for ASA and SSA #1 - a case of ASA --> a side contained between two ...

*November 27, 2016*

**precalculus**

There are several question of your type in the Related Questions section below

*November 27, 2016*

**precalculus**

Vague question. are you converting an equation or a point with rectangular coordinates?

*November 27, 2016*

**Maths**

For any number, there are 10 possible digits for the unit place, one of those is the 2. so prob(your event) = 1/10

*November 27, 2016*

**Algebra**

compare: http://www.jiskha.com/display.cgi?id=1480210517

*November 26, 2016*

**Algebra**

find the vertex of the parabola. The t of the vertex tells you when it reached the maximum height, the h tells you what that height is.

*November 26, 2016*

**Math**

equation: y = 100 (2)^(t/3.2) .. .. to get 450 bacteria 450 = 100 (2)^(x/3.2) 4.5 = 2^(x/3.2) take log of both sides and use log rules (x/3.2)log 2 = log 4.5 x/3.2 = log 4.5/log2 x = 6.944 hrs. or appr 7 hours

*November 26, 2016*

**precalculus**

How does this post differ from this one? http://www.jiskha.com/display.cgi?id=1480198638

*November 26, 2016*

**PreCalc**

let f(x) = 2x^3+x^2-8x+3 f(1) ? 0 f(-1) = -2+1+8+3 ? 0 f(3) ? 0 f(-3) ? 0 f(3/2) = 0 , yeahhhh, 2x-3 is a factor by long division, 2x^3+x^2-8x+3 = (2x-3)(x^2 + 2x -1) the quadratic has roots of x = -1 ± ?2 looking at the graph of y = 2x^3+x^2-8x+3 -1-?2 < x < -1+?...

*November 26, 2016*

**Algebra**

let the distance from Seattle to wilderness be x miles x/420 + x/300 = 6 times 2100 the LCM 5x + 7x = 12600 x = 1050 miles

*November 26, 2016*

**Trigonometry**

look at the cos^-1 (x/3) construct a triangle with base of x and hypotenuse of 3 by Pythagoras: r^2 = x^2 + y^2 3^2 = x^2 + y^2 y^2 = 9 - x^2 y = ?(9-x^2) so we want the tangent tan (cos^-1 x/3) = opposite/adjacent = ?(9-x^2)/3

*November 26, 2016*

**precalculus**

(3(cos(5pi/4)+i sin (5pi/4) ) )^8 = 3^8(cos 8(5?/4) + i sin 8(5?/4)) = 6561( cos 10? + i sin 10?) = 6561( 1 + i(0) ) = 6561 B (3-3i)^6 let z = 3-3i, so we want z^6 r = ?(9 + 9) = ?18 = 3?2 plot (3,-3) which is in IV, so Ø = 315° or 7?/4 z = 3?2(cos 7?/4 + i sin 7?/4...

*November 26, 2016*

**precalculus**

I checked the first 4, they were ok you seem to know what you are doing.

*November 26, 2016*

**Trigonometry**

a) isn't arcsin(sin(?)) the inverse of itself? so 13?/16 b) and c) same thing, except by definition arcsin( ..) will give you the smallest positive angle so arccos(cos(-?/18) = ?/18 d) arcsec(-?2) the angle Ø so that secØ = -?2 or cosØ = (-1/?2) &...

*November 26, 2016*

**precalculus**

a) ok b) (i-j)-(18i+27i) = -17i - 28j c) (5i-5j)-(30i+54j) --> you did 5u - 5v instead of 5u-v

*November 26, 2016*

**pre calculus**

250 pounds at 45° ---> (250cos45, 250sin45) 130 pounds at -60° ---> (130cos(-60), 130sin(-60) ) Resultant = (250cos45, 250sin45)+(130cos(-60), 130sin(-60) ) = (125?2, 125?2) + (65 , -65?3) = ( 125?2 + 65 , 125?2 - 65?3) = appr (241.7767 , 64.1934) maginitude...

*November 26, 2016*

**Discrete Math**

if you meant: x^1 + x^2 + x^3 + 2x^4 + x^5 = 68 there are none http://www.wolframalpha.com/input/?i=solve+x+%2B+x%5E2+%2B+x%5E3+%2B+2x%5E4+%2B+x%5E5+%3D+68

*November 26, 2016*

**pre calculus**

checking for right-angled triangle: is 100^2 = 55^2 + 85^2 ? NO so let's find the smallest angle by the cosine law: 55^2 = 100^2 + 85^2 - 2(100)(85)cosØ cosØ = 14200/17000 = .83529.. Ø = 33.35..° , (I stored it for accuracy on my calculator So area...

*November 26, 2016*

**pre calculus**

u=<0,-4>, v=<-2,-8> a) 2v+u = <-4,-16) + <0,-4) = <-4, -20> b) 5u - v = <0,-20> - <-2,-8) = <2, -12> c) do this one the same way

*November 26, 2016*

**Mathmatics help please**

clearly 25 and 15

*November 26, 2016*

**Maths help asap please**

3c-7 > 5c+4 3c - 5c > 4+7 -2c > 11 c < -11/2 or c < -5.5 so the smallest integer that is a solution is c = -6 check: if c = -6, -18 - 7 > -30+4 -25 > -36 , true! if c = -5 -15-7> -25+4 -22 > -21 , false

*November 26, 2016*

**Math**

subtract 2 from each part, and you are done -3<x+2<3 -3-2 < x+2-2 < 3-2 -5 < x < 1 ---> ( x lies between -5 and 1 )

*November 26, 2016*

**Math**

nothing wrong with that you could just use the trig-vector notation resultant = (10cos60,10sin60) + (20cos120,20sin120) + (30cos180,30sin180) + (40cos270,sin270) = (5, 5?3) + (-10, 10?3) + (-30, 0) + (0, -40) = ( -35, 5?3-40 )) your sketch will confirm that

*November 26, 2016*

**Trigonometry**

Both Steve and I both told you what was wrong with the wording of the question. http://www.jiskha.com/display.cgi?id=1480115359 Did you even look at the responses?

*November 25, 2016*

**Math**

(2 x 3)>2 - 5>2 is a false statement. you are basically saying: 6 > 2-5 > 2 6 > -3 > 2 the part 6 > -3 is true, but -3 > 2 is nonsense To ask "evaluate" the expression makes no sense Hey, wait a minute! Did you mean (2 x 3)^2 - 5^2 ?? then you...

*November 25, 2016*

**math**

You can't just drop the variable. 5(2x + 7) = 10x + 35 Now you can see that we can't add the 10 and 35 since they are "unlike" terms

*November 25, 2016*

**Math**

correct

*November 25, 2016*

**math**

The 14M, the 3M and the 1M are all expenses so what is 20 - (14+3+1) ?? I get 2 Million

*November 25, 2016*

**Calculus AB**

3y^3 + 2x^2 = 5 9y^2 dy/dx + 4x = 0 dy/dx = -4x/9y^2 when y = 1 , 3 + 2x^2 = 5 2x^2 = 2 x = ± 1 , but in quadrant 1, x = 1 dy/dx = -4(1)/9 = -4/9 equation of tangent: y-1 = (-4/9)(x-1) 9y-9 = -4x + 4 4x + 9y = 13 check: http://www.wolframalpha.com/input/?i=plot+3y%5E3+%...

*November 25, 2016*

**Trigonometry**

y = cos(3?/4 - x) already is a single function of x, namely the cosine function. I don't understand what else you want to do with it. We know: using cos(A-B) = cosAcosB + sinAsinB cos(3?/4 - x) = cos 3?/4 cosx + sin 3?/4 sin x = -?2/2 cosx + ?2/2sinx = ?2/2 (sinx - cosx...

*November 25, 2016*

**Math**

In the original number let the unit place by x then the tens place is 2x, (obviously x < 5) then the number in terms of its value is 10(2x) + x and the number reversed is 10x + 2x the difference between these two is 36, just translate this into Math. 10(2x) + x - (10x + 2x...

*November 25, 2016*

**Math**

clearly the 5 has to go in the unit position for the number to be odd At the front, what would be bigger, something 6 hundred or something 8 hundred?

*November 25, 2016*

**Mathematics**

let his sales be x .06x + 6000 = 10200 solve for x

*November 25, 2016*

**Maths**

330/x - 330/(x+5) = 1/2 That's ok, we end up with a quadratic. Multiply each term by 2x(x+5) 660(x+5) - 660x = x(x+5) 660x + 3300 - 660x = x^2 + 5x x^2 + 5x - 3300 = 0 (x-55)(x+60) = 0 x = 55 or x = -60, we would reject the -60 So your inward speed is 55 km/h, the return ...

*November 25, 2016*

**math**

90 = 2x3x3x5 since each pair of equal factors produces a perfect square, we have 3x3, a perfect square. So all we need is another 2 and another 5 How about 2x2x3x3x5x5 = 900 900 = 30^2 , so it is a perfect square, and it is divisible by 90

*November 24, 2016*

**math-factors and multiples**

both 40 and 32 divide by 8 both a^3 and a^2 divide by a^2 The GCF is 8a^2

*November 24, 2016*

**math**

It is 30a^2

*November 24, 2016*

**math**

5 ? m/-3 + 18 add m/3 to both sides 5 + m/3 ? 18 m/3 ? 13 m ? 39 or 5 ? m/-3 + 18 -13 ? m/-3 times -3 39 ? m m ? 39 , same as above

*November 24, 2016*

**math**

the slope of the 2nd is -2/16 = -1/8 which is the negative reciprocal of the slope of the first. Thus, the lines are perpendicular.

*November 24, 2016*

**math**

I assume we are factoring 25m^6-121m^4 = (5m^3 - 11m^2)(5m^3 + 11m^2)

*November 24, 2016*

**Calculus applications**

let the height be 100 cm^3 ?r^2 h = 100 h = 100/(?r^2) S = 2 circles + the sleeve = 2?r^2 + 2?rh = 2?r^2 + 2?r(100/(?r^2)) = 2?r^2 + 200/r you typed it wrong, it should have been 2?r^2 + 200 r^-1 dS/dr = 4?r - 200/r^2 = 0 for a min of S 4?r = 200/r^2 r^3 = 200/(4?) = 25/? r...

*November 24, 2016*

**Math**

Now: Marcus ---- x John ------ x+10 5 years from now: John's age = x+15 5 years ago: Marcus = x-5 3(x+15) = x-5 that would give you the silly answer of x = -25 checking now Marcus is -25 John is -15 5 years from now, John is -10 and 5 years ago Marcus was -30 sure enough 3...

*November 24, 2016*

**maths**

Without any restrictions, number of committees = C(10,4) = 210 include at least one woman ---> exclude cases of all 4 being men number of ways = 210 - C(5,4) = 205

*November 24, 2016*

**math**

now: daughter ---- x years Mary -------- 3x years 4 years ago: daughter : x-4 Mary : 3x-4 (x-4)(3x-4) = 40 3x^2 -16x + 16 = 40 3x^2 - 16x - 24 = 0 I was expecting it to factor, hoping for whole number solution, but .... x = (16 ± ?544)/6 = 6.55 or a negative check: if ...

*November 24, 2016*

**Math**

let the two numbers be 9x and 3x then 9x + 3x = 72 .. x = 6 sub into my definition to get the numbers.

*November 24, 2016*

**Math**

Find the midpoint of AB, then use your "distance between two points" formula to get CM .

*November 24, 2016*

**Maths**

let the numbers be x and x+1 solve: x + x+1 = 39

*November 24, 2016*

**math**

your first equation should have been 4x +5 = 37 instead of 4x(5) = 37 but then you miraculously switched it to the right one as you solved it. The answer is correct

*November 24, 2016*

**Further mathematics**

x^2 + y^2 = 5xy complet the square: x^2 + 2xy + y^2 = 7xy (x+y)^2 = 7xy take log of both sides 2log(x+y) = log 7 + logx + logy 2log(x+y) - log7 = logx + logy 2log(x+y) - 2log 7^(1/2) = logx + logy 2[ log(x+y) - log ?7] = logx + logy 2 log( (x+y)/?7 ) = logx + logx as required ...

*November 23, 2016*

**algebra~help me**

18^(4-4y)=54(?2)^(3y-2) take log of both sides (4-4y)log18 = lof54 + (1/2)(3y-2)log2 4log18 - 4ylog18 = log54 + (3y/2)log2 - log2 4log18 - log54 + log2 = y( (3/2)log2 + 4log18) 3.58972... = (5.4726...) y y = .655941

*November 23, 2016*

**Calculus**

so considering t = 0 to correspond with 2016 1000 = A 3^0 , but 3^0 = 1 A = 1000 b) y(5) = 1000 3^(4/3) = .... Use your calculator c) 100000 = 1000 3^(t/4) 1000 = 3^(t/4 take log of both sides log 1000 = log 3^(t/4) 3 = (t/4)log 3 t/4 = 3/log3 t = 12/log3 = appr 25.15 years iv...

*November 23, 2016*

**math**

Assuming the farm is a rectangle ... length --- x width = 39 2x + 2(39) = 187.2 find x once you have x, take x/39

*November 23, 2016*

**algebra**

How about you showing me some of your steps, now that I have done two very similar to this one for you ?

*November 23, 2016*

**algebra**

breath (width) ---- x length -----------x+12 2x + 2(x+12) = 144 carry on

*November 23, 2016*

**algebra**

smaller --- x larger --- y Now just translate into Math. 3(y - x) = y+3 3y - 3x = y+3 3x - 2y = -3 ** 3(y+x) = 8x + 2 3y + 3x = 8x + 2 5x - 3y = 2 *** solve ** and *** You should get two whole numbers.

*November 23, 2016*

**Differential calculus**

If expanded you would get a standard cubic Its x-intercept are (2,0), (-1,0) and (-3,0) http://www.wolframalpha.com/input/?i=plot+y%3D(x-2)(x%2B1)(x%2B3)

*November 23, 2016*

**maths**

let the two numbers be 5x and 7x "it's lam is 210" , I have no clue what that means.

*November 23, 2016*

**maths**

I will assume you meant the ninetieth term. If a and d are the first term and common difference respectively, then term(90) = 30 a + 89d = 30 a = 30-89d sum(17) = (17/2)(2a + 16d) = (17/2)(2(30-89d) + 16d) = (17/2)(60 - 162d)

*November 23, 2016*

**Math**

Did you make a sketch? 1) sin30° = h/15 h = 15sin30 = 15(1/2) = 7.5 m Very unsafe way to place a ladder, the angle should be > 76° at the ground 2) in reference to the 60° angle, the 13 m is the "adjacent" and you want the "opposite" side ...

*November 22, 2016*

**Statistics**

numer of ways = 15 x 14 x 12 = .... (assuming the order matters, and you have specified positions)

*November 22, 2016*

**Math**

correct (the jet stream does not just flow over the US )

*November 22, 2016*

**I dont know**

they can be any (x,y) such that x^2 + y^2 = 64 e.g. (2 , ?60), (?39 , 5) , (8,0), (8,0), (4?2 , 4?2) etc

*November 22, 2016*

**Algebra2**

but log8 2 = 1/3 so log8 (a/2) = log8 a - 1/3

*November 22, 2016*

**math**

equilateral ---> all sides are equal, so 3x+2 = 2y-x 4x + 2 = 2y 2x + 1 = y also 3x+2 = y + 3 3x+2 = 2x+1 + 3 x = 2 then y = 5 so each side is 3x+2 = 8 and the perimeter is 24

*November 22, 2016*

**Math**

9/(2x) = 15/12 "cross-multiply" 30x = 108 x = 108/30 = 18/5 or 3.6

*November 22, 2016*

**Math**

amount of peaches --- x lbs amount of melons ---- y lbs amount of apples ----- 100 - x - y lbs (assume both x and y are whole numbers) 10x + 3.5y + .5(100-x-y) = 100 double every term 20x + 7y + 100 - x - y = 200 19x + 6y = 100 x = (100 - 6y)/19 , clearly 0 < y < 6 by ...

*November 22, 2016*

**10th Grade Math**

To have a triangle, the sum of any two sides must be greater than the third side. look at C 5+10< 18 all the others form a triangle

*November 22, 2016*

**maths**

The volume of 2 similar objects is proportional to the cube of its linear sides 320/x = 8^3/6^3 512x = 69120 x = 69120/512 = 135 or the side ratio is 6/8 = 3/4 old volume = 8(l)(w) = 320 lw = 40 new volume = 6(3l/4)(3w/4) = 54/16 lw = (54/16)(40) = 135

*November 22, 2016*

**maths**

surface area of smaller = 4? r^2 surface area of larger = 4?(3r)^2 = 36?r^2 which is 9 times as great or the area of similar objects is proportional to the square of their linear dimension, so 1^2 : 3^2 = 1 : 9

*November 22, 2016*

**Algerbra**

so it will differ only in the constant let the equation be y = -4x + b but (-8,-4) lies on it, so -8 = -4(-8) + b solve for b and write the equation.

*November 22, 2016*

**Trigonometry**

tanØ = 4/1 = 4 Ø = 75.96 The angle should be 76° by ratio: 4/1 = 16/x x = 4

*November 22, 2016*

**Math**

number of adult tickets sold = 3x number of children tickets sold = 5x 5x = 3x + 180 take over.

*November 22, 2016*

**math**

LCD is 5b a/5 +4/b = ab/5b + 20/5b = (ab + 20)/(5b)

*November 22, 2016*

**Algebra**

slope of main street = (33-17)/(-22+2) = -4/5 so slope of Grimes Blvd = +5/4 y - 9 = (5/4)(x-80) y = (5/4)x - 100+ 9 y = (5/4)x - 91

*November 22, 2016*

**Math**

Follow the same steps I just showed you in your previous problem.

*November 22, 2016*

**Math**

number of girls ---- 7x number of boys ---- 5x "there are 8 more girls 10 boys" makes no sense are you saying, "there are 8 more girls than boys" ? which translated into math would be 7x = 5x+8 take it from here

*November 22, 2016*

**maths**

done, see below

*November 22, 2016*

**algebra**

number of nickels ---- x number of dimes ----- x+10 number of quarters = 37-(x + x+10) = 27 - 2x value of coins = 5x + 10(x+10) + 25(27-2x) = 5x + 10x + 100 + 675 - 50x = 775 - 35 x

*November 22, 2016*

**Math**

I don't know, you did not state the rate of interest.

*November 22, 2016*

**maths**

volume of wooden rod = ?(2^2)(6) = 24? volume which is submerged = 12? So the volume in the cylinder will change by that amount ?(4^2)h = 12? 16h = 12 h = 12/16 cm = 3/4 cm new depth = 4+3/4 cm = 19/4 cm or 4.75 cm

*November 22, 2016*

**maths**

" ... is placed in the tin or floats exactly half 2.what is the New depth of water " Retype in proper English so I can understand it.

*November 22, 2016*