Saturday

December 10, 2016
Total # Posts: 36,953

**MATH 123**

1((1/2)^(t/5730) = .55 (.5)^(t/5730 = .55 take log of both sides log (.5)^(t/5730 = log .55 (t/5730) log .5 = log .55 t/5730 = log .55/log .5 t = 5730(log .55/log .5) = appr 4942 years

*November 15, 2016*

**math**

x + y ? 20 9x + 12y ? 200 whatever graph they give you, there should be one with the region below x+y = 20 shaded in AND the region above 9x + 12y = 200 shaded in. It should look something like this: http://www.wolframalpha.com/input/?i=plot+x+%2B+y+%3D+20+,+9x+%2B+12y+%3D+200...

*November 15, 2016*

**math**

When you have a function such as P(x) = 2(x-3)(x-4) you could also write it as y = 2(x-3)(x-4) So when they speak of the zeros of the function, they are really describing the x's that make y = 0 that is: 2(x-3)(x-4) = 0 Now think about the answer of 0 after a ...

*November 15, 2016*

**maths**

fog = f(g(x)) = f(2x-3) = (2x-3)^2 + 3(2x-3) + 1 = 4x^2 - 12x + 9 + 6x - 9 + 1 = 4x^2 - 6x + 1 now do gog in the same way

*November 15, 2016*

**Math**

A : B = 5:11 = 10 : 22 = ... = 10x : 22x A : B : C = 2:3:15 = 10:15:75 = ... = 10x:15x:75x in solution X we have 10x/(22x) of A so amount of A in 400 L ofX is (10/22)(400) = appr 181.8 L in solution Y amount of C in 400 L = 75x/(100x)(400) = 300 L

*November 15, 2016*

**maths**

qD(9) = 8000/(81+1) = appr 97.56 qD(8.5) = 8000(72.25+1) = appr 109.22 So, what do you think?

*November 15, 2016*

**algebra**

just translate .... four times a number --- 4x fourteen times its reciprocal --- 17(1/x) or 17/x the sum of ---> + is 15 ----> = 15 so: 4x + 17/x = 15 How easy was that?

*November 15, 2016*

**Algebra**

woman's rate ---- 1/x man's rate ----- 1/(x-5) , where x > 5 combined rate = 1/x + 1/(x-5) = (x-5 +x)/(x(x-5)) = (2x-5)/(x^2 - 5x) (2x-5)/(x^2 - 5x) = 1/6 x^2 - 5x = 12x - 30 x^2 - 17x + 30 = 0 (x-15)(x-2) = 0 x = 15 or x =2 , but x > 5 x = 15 The woman can do ...

*November 15, 2016*

**Math**

1-(-2)^2*(-1)^3 = 1 - 4(-1) = 1 + 4 = 5

*November 15, 2016*

**maths**

Make your sketch. Method 1, complete the parallelogram and find the diagonal x^2 = 5^2 + 3^2 - 2(5)(3)cos 150° = 59.9807... x = appr 7.74 (exact value: x^2 = 34 + 30?3/2 = 34 + 15?3 x = ?(34 + 15?3) ) method 2 place vector P along the horizontal so vector P = (5,0) vector ...

*November 15, 2016*

**Algebra**

same thing e.g. (1/2)(12) = 6 12/2 = 6 as to your question, mom's age ---- x Rowena's age -- x/2 8 years ago: mom ---- x-8 Rowena -- x/2 - 8 x/2 - 8 = (1/3)(x-8) times 6, the LCD 3x - 48 = 2(x-8) 3x - 48 = 2x - 16 x = 32 Mom is 32, Rowena is 16 check: 8 years ago, the ...

*November 15, 2016*

**math**

Arggghhhh!

*November 15, 2016*

**Maths**

How about this approach? A:B = 2:3 or 6:9 B:C = 9:5 ---> notice the value of B is the same so A:B:C = 6:9:5 or 6x:9x:5x 6x+9x+5x = 400 20x = 400 x = 20 so A got 6(20) = 120 B got 9(20) = 180 C got 5(20) = 100

*November 15, 2016*

**Math**

I am going to assume you meant (2x-7)/4 - (x-6)/7 = 0 then (2x-7)/4 = (x-6)/7 multiply both sides by 28, the LCD 7(2x-7) = 4(x-6) 14x - 49 = 4x - 24 10x = 25 x = 25/10 = 5/2 or 2.5 or 2 1/2

*November 14, 2016*

**Math**

50x^4 / (12x) = 25x^3 /6 or (25/6)x^3

*November 14, 2016*

**thomas middle such**

it is less than 300 --> 1xx or 2xx the hundreds digit is 3 less than the ones digit ---1x4 or 2x5 the tens digit is 5 more than the hundreds digit ---> 164 or 274 the sum if the digits is 11 ----> 164

*November 14, 2016*

**algebra**

original: width --- x length --- 5x , (it said so) new dimensions: length = 5x - 3 width = x+10 perimeter = 2* width + 2*length = 2(x+10) + 2(5x-3) = 374 2x + 20 + 10x - 6 = 374 12x = 360 x = 30 So the original rectangle had a width of 30 m and a length of 150 m

*November 14, 2016*

**algebra**

4b/2 + 3 = 11 + b 2b + 3 = 11 + b, since 4/2 = 2 2b - b = 11-3 b = 8 or 4b/2 + 3 = 11 + b multiply every term by 2 4b + 6 = 22 + 2b 4b - 2b = 22 - 6 2b = 16 divide both sides by 2 b = 8

*November 14, 2016*

**math**

the effective distance: 16 km east and 8 km north ---> right-angled triangle hint: Pythagoras

*November 14, 2016*

**math**

Poorly worded question. Are we to assume that some questions were skipped, and no reward or penalty for skipped questions? I will assume that. rights ---- x wrongs --- y skipped -- 40-x-y) 5x - 3y + 0(40-x-y) = 70 5x - 3y = 72 y = (5x-70)/3 , clearly 14 ? x ? 40 , x+y ? 40 ...

*November 14, 2016*

**Math**

Now: Benny ---- x years Apple ---- 38-x 6 years ago: Benny ---- x-7 Apple ----- 38-x - 7 = 31-x 31-x = 3(x-7) solve for x, and sub into my definitions

*November 14, 2016*

**Maths**

let the perpendicular height be 4x let the slant height be 5x (4x)^2 + 6^2 = (5x^2 16x^2 + 36 = 25x^2 carry on, of course you would reject the negative value of x after taking the square root at the end.

*November 14, 2016*

**Maths**

Think of the 5 kids standing in a row, and in each row changing positions 1 ---> 3 2 ---> 5 3 ---> 1 4 ---> 2 5 ---> 4 At the start,,,: 1 2 3 4 5 ---> A B C D E after 1 round: 3 4 1 5 2 ---> C D A E B after 2 round: 1 5 3 2 4 ---> A E C B D after 3 ...

*November 14, 2016*

**math**

depends where you want the water spout to be. It would make sense to have the spout at the origin. Then the zeros of the function would be (0,0) and (8,0) and the vertex would be at (4,6) height = a(x - 4)^2 + 6 but (0,0) lies on it, thus: 0 = a(0-4)^2 + 6 16a = -6 a = -3/8 ...

*November 14, 2016*

**Aljebra**

original number in first box --- x original number in 2nd box --- 123-x after shift: first box ----- x-10 2nd box --- 123-x + 10 = 133-x 133-x = 2(x-10) solve for x

*November 13, 2016*

**Math**

3?(x - 1) + 6 when x = 26 = 3?25 + 6 = ....

*November 13, 2016*

**pre algebra**

adult tickets ---- x children tickets --- 2x + 15 solve for x: 12x + 5(2x+15) = 1920

*November 13, 2016*

**pre algebra**

follow the same method and steps I just showed you in your other posts. The two questions are of the same structure.

*November 13, 2016*

**intermediate maths**

granddaughter's age---- x James' age --------- 6x 2 years from now: granddaughter's age --- x+2 James' age ---------- 6x + 2 6x+2 = 5(x+2) solve for x

*November 13, 2016*

**Algebra**

speed of slower rider --- x km/h speed of faster rider ---- 2x km/h distance gone by slower = 3(x) = 3x distance gone by faster = 3(2x) = 6x 3x + 6x = 90 9x = 90 x = 10 rate of slower rider = 10 km/h rate of faster rider = 2(10) = 20 km/h

*November 13, 2016*

**Calculus**

let the point of contact be P(a,b) let A be (1,7) slope of AP = (b-7)/(a-1) the closest point would be where the tangent at P is perpendicular to AP 2y dy/dx = 1 dy/dx = 1/(2y) so at P, the slope of the tangent is 1/(2b) so (b-7)/(a-1) = -2b b-7 = -2ab + 2b -b = -2ab + 7 2ab...

*November 13, 2016*

**math**

In a parallelogram Abcd angle add ??? side an ???? e ????? x+y ???? wow!

*November 13, 2016*

**Math**

Just follow the definition: a*b means 3a^2+b 3*1 means 3(3^2) + 1 = .....

*November 13, 2016*

**Math**

number correct --- x , 0 ? x ? 20 number wrong ---- y number skipped ---- 20-x-y 5x - y + 0 = 72 y = 5x - 72 y ? 0 if x = 14, y = -2 , not possible if x = 15 , y = 3 , skipped = 2 if x = 16, y = 8 , not possible , x+y>20 so he got 16 right, 8 wrong, and skipped 2 check: 5(...

*November 13, 2016*

**Math**

not arithmetic nor geometric gave up and checked with Wolfram found: term(n) = (7(3^n) - 3)/6 http://www.wolframalpha.com/input/?i=pattern+%7B3,+10,+31,+94%7D quite obscure, perhaps more terms would have helped.

*November 13, 2016*

**Math**

mmmhhhh when x=1 , 3+2x = 3+2(1) = 5 when x=2, 3+2x = 3+2(2) = 7 when x = 3 ..... continue

*November 13, 2016*

**Math**

number of girls --- x number of boys --- (5/11)x x - (5/11)x = 114 (6/11)x = 114 x = 114(11/6) = .... take over

*November 13, 2016*

**Math**

1:2:1/2 = 2:4:1 -----> ratios usually are not expressed in fraction form let their shares be 2x, 4x, and x but x = 48 so 2x = 96 and 4x = 192 add them up

*November 13, 2016*

**Calculus**

You did not do exactly the same, your slope was -3/5, different from mine. (another example of why I prefer traditional class room instructions, where the learning of math is not just "answer based" )

*November 13, 2016*

**Calculus**

How did you get the slope to be -3/5 ?? let the x-intercept be A(a,0) and the y-intercept be B(0,b) label point (3,5) as P By ratios in similar triangles: (a-3)/5 = 3/(b-5) ab-5a-3b+5 = 15 b(a-3) = 5a b = 5a/(a-3) Area of triangle = (1/2)ab = (1/2)(a)(5a/(a-3) ) = 5a^2/(2a-6) ...

*November 13, 2016*

**Math**

right now: x + 7x = 976 x= 122 Aaron has 122 cards and Ben has 854. after the give-away of k cards: ben has 854-k Aaron has 122+k Aaron has 3 times as many as Ben 122+k = 3(854 - k) 122+k = 2562 - 3k 4k = 2440 k = 610 check: after the exchange Ben has 854-610 = 244 Aaron has ...

*November 12, 2016*

**Maths**

3^9 + 3^12 + 3^15 + 3^n = 3^9(1 + 3^3 + 3^6 + 3^(n-9) ) = 3^9(757 + 3^(n-9)) 3^9 is a perfect cube, so all we need is (757 + 3^(n-9)) to be a perfect cube, clearly n >9 perfect cubes past 757 with 3^(n-9) as the 2nd number: 1000 243 <---- well, that was lucky 1331 574...

*November 12, 2016*

**Calculus**

let the height be h then h^2 + b^2 = 20^2 h = (400-b^2)^(1/2) Area = (1/2)(bh) = (1/2)(b)(400 - b^2)^(1/2) d(Area)/dt = (b/2)(1/2)(400-b^2)^(-1/2) (-2b db/dt) + (1/2)(db/dt)(400 - b^2)^(1/2) = -b^2 (db/dt)/?(400-b^2) + (1/2)(db/dt)?(400-b^2) when b = 11 and db/dt = 4 d(Area)/...

*November 12, 2016*

**math**

number of ways to give the fruits = 5!/(3!2!) = 10 (you could list them) Bananas at least two days in a row: BABAB is the only case where two or more B could not be together. Look at your list from above prog(at least two B's in a row) = 9/10

*November 12, 2016*

**maths**

Susan's age now ---- x Mary's age now ------3x Three years ago: Susan ---- x-3 Mary ----- 3x-3 x-3 + 3x-3 = 22 continue

*November 12, 2016*

**Algebra**

good road ---- x km poor road ----- 48-x km time on good road = x/72 time on poor road = (48-x)/48 x/72 + (48-x)/48 = 3/4 times 144 , the LCD 2x + 3(48-x) = 108 carry on, easy from here

*November 12, 2016*

**Maths**

without a calculator... let a=20142014 then 20142015 = a+1 then 20152015 = a + 1 + 1000 = a+1001 then 20152014 = a+1000 20142015×20152014 – 20142014 ×20152015 = (a+1)(a+1000) - a(a+1001) = a^2 + 1001a + 1000 - a^2 - 1001a = 1000

*November 12, 2016*

**Algebra**

2x^3 - 5x^2 - 5x - 1 = 0 let f(x) = 2x^3 - 5x^2 - 5x - 1 try f(1) = 2 - 5 - 5 - 1 ? 0 try f(-1) = -2 - 5 + 5 - 1 ? 0 try f(1/2) = 1/4 - 5/4 - 5/2 - 1? 0 try f(-1/2) = -1/4 - 5/4 + 5/2 - 1 = 0 , yeahh! so (2x + 1) is a factor and x = -1/2 by long algebraic division, which I ...

*November 11, 2016*

**Math -fractions word problems**

total number of students ---- x number of boys ----- (3/7)x number of girls ------(4/7)x (4/7)x = (3/7)x + 4 times 7, the LCD 4x = 3x + 28 x = 28 boys: (3/7)(28) = 12 girls = 28-12 = 16

*November 11, 2016*

**intergrated science**

I will assume that Calculus is part of your integrated science course. a = 2 then v = 2t + c at the beginning of the observation, t = 0 , v = 24 so 24 = a(0) + c ----> c = 24 v = 2t + 24 when t = 8 v = 2(8) + 24 = 40 m/s or, simply .... for each of the 8 seconds the ...

*November 11, 2016*

**calculus**

your values of x = -2, 3 are the x-intercepts, and you don't need a derivative to find them dy/dx = (x-3)(2/3)(x+2)^(-1/3) + (x+2)^(2/3) = (1/3)(x+2)^(-1/3) [2(x-3) + 3(x+2)] = (1/3)(5x)(x+2)^(-1/3) = 0 for a max/min of y ----> 5x = 0 or (x+2)^(-1/3) = 0 ---> no way ...

*November 11, 2016*

**math- Trigonometry**

I agree with Scott. For the given date, the calculations are correct. In reality, the question is absurd. Using Pythagoras, the height of the lighthouse would have to be appr 8.9 km high. and, using our given angle of 65.91..° tan 65.91 = height/4 height = 4tan 65.91 = ...

*November 11, 2016*

**Math**

or 15 machines 15 minutes to make 500 raviolis 75 machines 15 minutes to make 2500 raviolis 75 machines 15(2.4) minutes to make 2500(2.4) raviolis 75 machines 36 minutes to make 6000 raviolis (the 2.4 comes from 6000/2500)

*November 11, 2016*

**maths**

I assume you are solving? from the 2nd: y = -2x-4 sub into the first 3x - 2(-2x - 4) = 1 3x + 4x + 8 = 1 7x = -7 x = -1 back into y = -2x - 4 y = -2(-1) - 4 = -2 x = -1 , y = -2

*November 11, 2016*

**Math**

Assuming that x is the length of the missing parallel side ... area of trapezoid = (x+15)(10)/2= 5x + 75 area of triangle = (1/2)(15)(10) = 75 5x + 75 < 2(75) 5x < 75 x < 15 but clearly x has to be positive 0 < x < 15 looks like a common sense type of question ...

*November 11, 2016*

**finite math**

mortgage after downpayment = 140,000 i = .09/12 = .0075 n = 30(12) = 360 payment = p p(1 - 1.0075^-360)/.0075 = 140000 p(124.2818657.) = 140000 p = $1126.47

*November 11, 2016*

**finite math**

Follow the same steps I just showed you here http://www.jiskha.com/display.cgi?id=1478848733

*November 11, 2016*

**Math**

1/6 of the 3/2 pepperoni's remain or 1/4 this is (14)/4 or 1/16 of the original amount

*November 11, 2016*

**Math**

distance covered in one rotation = 25? inches 65 miles/hr = 65*12*5280 inches/hour = 65*12*5280/3600 inches/sec number of rotations = 65*12*5280/3600 ÷ (25?) = 14.56.. / sec or appr 15 rotations per second check: distance in 1 second = 14.56*25? = appr 1143.5 inches = ...

*November 11, 2016*

**Statistics**

prob(ace) = 4/52 = 1/13 prob(5 aces with card replaced each time) = (1/13)^5 = ....

*November 10, 2016*

**Math**

did you notice that the third difference is 3 ? So it is a cubic messing around a bit I got term(n) = (n^3 - n^2 - 4)/2 so term(6) = (216 - 36 - 4)/2 = 88

*November 10, 2016*

**math**

68/104 = 17/26 This question has two correct choices as answers. Poorly designed question.

*November 10, 2016*

**matha**

What part of my previous reply to your same question did you not like ? http://www.jiskha.com/display.cgi?id=1478784506

*November 10, 2016*

**Math**

This year: number of middle schoolers --- 2x number of high schoolers ----- 7x but 2x = 18 x = 9 So this year there are 18 middle schoolers, and 63 high schoolers. Total = 81 Since all we know from the previous year is the ratio of 1:8 , and there were more last year: possible...

*November 10, 2016*

**Math**

I have no idea what that first part of your post is supposed to be. your problem: 53+59+65+...+233 We have to know how many terms. a=53, d=6, n= ? term(n) = a + (n-1)d 233 = 53 + 6(n-1) 180 = 6n - 6 6n = 186 n = 31 sum(31) = (31/2)(first + last) = (31/2)(53+233) = 4433 which ...

*November 10, 2016*

**Math**

(Log75+log9+log5)÷(log5+log45) = log(75*9*5) / log(5*45) = log 3375 / log 225 = log(25*9*15) / log(25*9) = log(5^2 * 3^2 * 15)/log(5^2 * 3^2) = log( 15^2 * 15) / log (15^2) = (log 15^2 + log 15)/ log 15^2 = (2log15 + log15)/(2log15) = 3log15/(2log15) = 3/2 I think I ...

*November 10, 2016*

**math**

After eliminating all the weird symbols, I got: Triangle ABC is a right triangle with right angle at A. Suppose AX is an altitude of the triangle, AY is an angle bisector of the triangle, and AZ is a median of the triangle, and angle XAY = 13°. If X is on BY, then what is ...

*November 10, 2016*

**Math**

let the sides be 2x, 3x, and 4x (notice 2x:3x:4x = 2:3:4 ) but 2x = 15 find x, then sub into my definitions

*November 10, 2016*

**Algebra**

one number ---- x the other ------(1/2)x x + (1/2)x = 18 double each term 2x + x = 36 continue

*November 10, 2016*

**matha**

I think you missed a zero in the original value, if the present value is 1,000,000, then after a 5% depreciation you have 95% left or 950,000. Insert or delete the zero as needed.

*November 10, 2016*

**Math grade 6, 4 operations**

Let the number of years be x 10+x + 7+x = 41 2x = 41 - 17 2x = 24 x = 12 It will happen in 12 years. check: in 12 years: Deepak will be 22 his brother will be 19, the sum will be 41

*November 10, 2016*

**Math grade 6, 4 operations**

Retype your question in English please.

*November 10, 2016*

**Maths**

Translate into English. "One-fourth of the sum of a number and seven is four less than three times the number." If the number is x (1/4)x + 7 = 3x - 4 x/4 - 3x = -11 times 4 x - 12x = -44 -11x = -44 x = 4

*November 10, 2016*

**math**

how about 3457 ?

*November 10, 2016*

**math**

4-8 -(-2) -17 = -4 + 2 - 17 = -2 - 17 = -19

*November 10, 2016*

**math**

17(1/2)^(t/5730) = 10 (1/2)^(t/5730) = 10/17 take log of both sides and use rules of logs (t/5730) log .5 = log10 - lot17 t/5730 = (1 - log17)/log.5 t = 5730(1 - log17)/log .5 = appr 4387 years

*November 9, 2016*

**statistic**

enter your data http://davidmlane.com/normal.html

*November 9, 2016*

**Algebra- Word Problem**

your second equation: 4x + 2y = 56 2x + y = 28 2x+y = 28 x+y = 40 subtract: x = -12 you are correct, the question is bogus!

*November 9, 2016*

**Math algebra**

amount of water added ---- x gallons .6(2500) + 0.0x = .25(2500 + x) solve for x

*November 9, 2016*

**Math**

rate = distance/time = 3(.25)miles / 4.5 min but 4.5 min = 4.5/60 hrs = .0075 hrs = .75/.0075 mph = 10 mph

*November 9, 2016*

**maths**

n = 5 payment --- p i = .06 p(1.06^5 - 1)/.06 = 30000 I get p = $5321.89

*November 9, 2016*

**Algebra 2**

It appears that there are at least 3 numbers let the first be x then the second is x+2 and the third is x-4 x + x+2 + x-4 ? 30 3x ? 32 x ? 10 2/3 Assuming that your numbers are whole numbers x could be 5, 6, 7, 8, 9, or 10 possible cases: 5, 7, 1, .... ---> others that add ...

*November 9, 2016*

**Math**

Number of games in one round = C(10,2) = 45 but they are playing two rounds, so total number of games = 90

*November 9, 2016*

**Math**

I read that as: ?(2x - 1) = x-2 square both sides 2x-1 = x^2 - 4x + 4 x^2 - 6x + 5 = 0 (x-5)(x-1) = 0 x = 5 or x = 1 since I squared, both answers must be verified in the original equation, if x = 1 LS = ?(2x-1) = ?1 = 1 RS = 1-2 = -1 so x ? 1 if x = 5 LS = ?(10-1) = 3 RS = 5-...

*November 9, 2016*

**Math**

remember, consecutive angles in a parallelogram have to be supplementary, that is, they add up to 180° let the angles be x and 3x x + 3x = 180 continue ....

*November 9, 2016*

**math**

Volume of water rise = ?(6^2)(2) = 72? volume of 1 sphere = (4/3)?(1.5)^3 = 4.5? number of spheres that caused the rise = 72?/4.5? = 72/4.5 = 16

*November 9, 2016*

**Math**

x+y=82 x-y = 16 add them to solve for x subtract them to solve for y

*November 9, 2016*

**Calculus AB**

first find the point where y = 1 x^2 + 2x(1) + 1 = 4 x^2 + 2x - 3 = 0 (x+3)(x-1) = 0 x = -3 or x = 1 but in quad I, the point is (1,1) use implicit differentiation: 2x + 2x(dy/dx) + 2y + 3y^2 (dy/dx) = 0 dy/dx (2x + 3y^2) = -2x - 2y dy/dx = (-2x - 2y)/(2x + 3y^2) = (-2-2)/(2+3...

*November 9, 2016*

**Math**

8/12 = x/9 solve for x

*November 9, 2016*

**Math**

(f o g)(x) is defined as f(g(x)) so f(g(x)) = f(x-1) , remember f(x) = 3x+4 f(g(x)) = 3(x-1) + 4 = 3x + 1 , same as bob or f(g(x)) = 3g(x) + 4 = 3(x-1) + 4 = 3x + 1 , like bob had in #2 (f o g)(-2) = f(g(-2)) ----> g(-2) = (-2)^2 = 4 = f(4) = 3(4) + 2 = 14 last one: Here is...

*November 9, 2016*

**The Tangent Function**

Label the original position as A and the second position as B, top of the lighhouse as P and its base as Q. ABQ is a straight line, AB = 40, angle B=25°, angle PAQ = 30°, AQ = x, and PQ = h I used to teach this question is 2 ways: 1. In triangle PBA, angle PAB = 150&...

*November 9, 2016*

**9th grade algebra (completing square)**

You seem to have a good grasp of doing these. I verified most of your answers by subbing them back into the original equation. All the ones I tried were correct. I suggest you take your calculator and test your answers.

*November 9, 2016*

**correction - math**

Y = 2x^2 + 3?x is NOT a function, since a quadratic must have the form y = ax^2 + bx + c that is, the exponents of the x term can only be 2 or 1 the term ?x is x^(1/2) Furthermore, the graph of a quadratic function is a parabola, the graph of Y = 2x^2 + 3?x looks like this, ...

*November 9, 2016*

**Math**

Since no condition is stated, that number would be C(9,5) or 126 There seems to be something missing here.

*November 9, 2016*

**pre calc**

amount = a (1/2)^(t/k), where k is the half-life period when t = 2, amount = .7a .7a = a(1/2)(2/k) .7 = (.5)^(2/k) take log of both sides and use log rules log .7 = (2/k)log .5 2/k = log .7 / log .5 = .514573... k = 2/.514573.. = 3.887 days the half-life is 3.89 days check: ...

*November 8, 2016*

**Math HELP HELP**

x^2+4x-41 = x^2+4x + 4 - 4 - 41 = (x+2)^2 - 45 expand and simplify to verify my answer

*November 8, 2016*

**pre calc**

N = a (2)^(t/20), where N is the number of bacteria, t is the number of minutes, a is the initial count, our problem. counting 7:00 as zero time and 5:00 am as t = 10 hrs = 120 minutes 1000000 = a(2)^(120/20) 1000000 = a(2)^6 64a = 1000000 a = 1000000/64 = 15625 of the germs ...

*November 8, 2016*

**Math**

Did you even look at the solution I gave you here http://www.jiskha.com/display.cgi?id=1478637677 This is the same type of problem. btw, the denominator on the right side factors to (x+3)(x-1)

*November 8, 2016*

**Algebra**

"j vaires directly with m and inversely with p" ----> j = km/p plug in the given, and solve for k

*November 8, 2016*

**MATH**

Your second equation IS a quadratic function. since the highest power you see is x^2. Sorry if you misunderstood. btw, don't say "square root of x", that would be ?x the term is "x squared"

*November 8, 2016*