Posts by Reiny

Total # Posts: 39,974

Math
Info: loonie - A $1 Canadian coin, showing a loon toonie - A $2 Canadian coin l+t = 45 ---> l = 45-t 1(45-t) + 2t = 67 45 - t + 2t = 67 continue

math
decrease = 15400-12950 = ... percent decrease = 100*decrease/15400 =

Math
what is 100*620/900 ?

math
now: Victoria --- x years old Devante ----- x+2 5 years from now: Victoria ---- x+5 Devante ----- x+7 solve for x, sub back into definitions x+5 + x+7 = 82

Marh
length --- 5x m width ----- 3x m Area = 15x^2 m^2 15x^2 *.84 = 624.75 solve for x, and from there find the length and width. Perimeter = 2length + 2 width = 10x + 6x = 16x cost of fencing = 4(16x) = 64x = .....

math
What problem?

math
the new line is parallel, so it must differ only by the constant. new line: y = x + b sub in (-7,1) to find b, then rewrite my equation

math .
#2 is correct #1 , your choice: "it starts with four ..." , really? Are you just guessing?

Pre-Calc
to find the inverse of a function, rewrite it in the form y = ..... interchange the x and y variable, then solve this new equation for y so y = 2x^3 + 1 inverse: x = 2y^3 + 1 2y^3 = x - 1 y^3 = (x - 1)/2 y = ( (x-1)/2 )^(1/3) check with a given point, in original let x = 3 , y...

Math
A container measuring 10 cm by 10 cm by 10 cm contains 1 L of water See if you can take it from there ?

Math
There are only a few of them. I am sure that in the time you took to post your question, you could have studied and learned at least 3 of them.

Math
Just noticed that Steve had already answered this question for you. https://www.jiskha.com/display.cgi?id=1507175220 Why did you re-post it ??

Math
What is the Least Common Multiple (LCM) of 6 and 8 ?

Finance
You can only compare "monies" if they are in the same "time" on your time-line. I would use the present as the reference point. Present Value of option I is $8400 (Clearly if you just paid them 8400, it's all done, right? PV of option II , i = .09/12...

statistics
draw a table of 6 rows and 6 columns, with the entries being the sums of the row and column count e.g. /// 1 2 3 4 5 6 1 ..2 3 4 5 6 7 2 ..3 4 5 6 7 8 3 .. 4 .. 5 ..6 7 8 9 10 11 6 Now count the "sums" that related to your question and you should be able to answer ...

Algebra: Please Help.
16y^3+48y^2=-36y First divide each term by 4 and "move" the term from the right side to the left 4y^3 + 12y^2 + 9y factor out a y y(4y^2 + 12y + 9) = 0 I see a perfect square y(2y + 3)^2 = 0 y = 0 or 2y+3 = 0 y = 0 or y = -3/2

Algebra: Please Help.
we are still ok with 10x^2+5x+5=0 now divide each term by 5 2x^2 + x + 1 = 0 doesn't factor, so we have to use the formula x = (-1 ± ?(1 - 4(2)(1)) )/4 = (-1 ± ?-7)/4 = (-1 ± ?7 i)/4 , a pair of complex numbers

Math
Assuming the payments are made at the end of a period to match the standard formulas outstanding balance = 10000(1.0058333...)^6 - 349.72( 1.0085333..^6 - 1)/.00853333... = .....

Math
at the 2.5 year mark i = .078/12 = .... n = 2.5(12) = 30 follow the same steps I just showed you in your next post

Calculus 1
at a time of t seconds ... let the radius of the circular water level be r let the height of the water be h 12/9 = h/r 12r = 9h 4r = 3h ----> r = 3h/4 V = (1/3)? r^2 h = (1/3)? (9h^2/4)(h) = (3/4)? h^3 dV/dt = (9/4) h^2 dh/dt 5 = (9/4)? (4) dh/dt solve for dh/dt

Math plz help
#2 | y+4| <1 Use your definition: y+4 < 1 AND -y-4 < 1 y < -3 AND -y < 5 y < -3 AND y > -5 or as they wrote it, -5 < y < -3

Math plz help
The last one is correct, the first two are wrong. Show me your steps so I can tell where you are going wrong.

Math plz help
I don't see your choices, so how can we check?

Math
What is the change in temperature? note, it will be negative, (dropping) What is the change in time from 1:00 pm to 9:00 pm average change in temperature per hour = total change in temperature / change in time = ...... degrees/hour

Math
10x + y= 2xy-9 y - 2xy = -9 - 10x y(1 - 2x) = -9-10x y = (-9 - 10x)/(1 - 2x) or y = ( 9+10x)/(2x-1) pick any x you want, evaluate the y. You can get as many values of x and y as you want. The only value of x you can't choose is x = 1/2 , since for that value you would be ...

Math
Why did you re-post the question after it has been answered??? https://www.jiskha.com/display.cgi?id=1507039066

Math
Nothing to solve, just multiply the two numbers. (Do 3 x 67, you should be able to do that in your head, then move the decimal 3 places to the left.) Of course you could also use your calculator.

Math
The way you typed it : 5^x + 2•5^x+1 = 3*5^x + 1 it does not factor over the rational numbers Secondly you did not say what type of number x is, let's assume x is a whole number, that is x = 0, 1, 2, 3, ... if you meant: 5^x + 2*5^(x+1) = 5^x( 1 + 2(5^1) ) = 5^x ( 11...

Math
first term --- a second term ---- ar a - ar = 2 a(1-r) = 2 sum to infinity = 15 a/(1-r) = 15 [a(1-r)][a/(1-r)] = 2(15) a^2 = 30 a = ± ?30 from a = ar+2 ?30 = ?30r + 2 r = (?30 - 2)/?30 = 1 - 2/?30 so we have ?30, ?30 + 2 , .... sum(5) = a (r^5 - 1)/(r-1) = .... = ..... ...

math
when it hits the ground, h = 0 0 = -4.9x^2 + 21.3x 4.9x^2 - 21.3x = 0 x(4.9x - 21.3) = 0 x = 0 , which corresponds to the moment she kicks the ball or x = 21.3/4.9 = appr 4.4 seconds

Math
I guess you could form columns for "n" and "left side" n ... LS 0 3 1 9 2 15 --- getting too big, looking for 2 on RS -1 -3 ---- too low, so n is between 0 and -1 1/2 6 ---- too high -1/2 -3 --- too low so between 0 and -1/2 -1/4 3/2 ----- too low so ...

math
notice that each new term is -3 times its previous, or tn = -3t(n-1) so we have -4, 12, -36, 108, -324

Algenra 1
both correct

math
This is the same type as your other post. Only this time you don't add anybody not belonging to either set.

Calculus
Do you actually expect somebody to do this assignment for you?

MATH
No, the 5 that do both are counted in the 16 geography students, AND the 18 chemistry students, so you are counting them twice number of students = 16+18 - 5 + 3 = .... make a Venn diagram to see.

Math
10(x+27) ? 26

Math
You will have to count the number of days from Feb 12 to June 23, I will leave that up to you and label it 'days' in I = PRT, your I = 40, R = ??, T = days/365 , P = 2000 40 = 2000(R)(days/365) R = 40(365)/(2000(days)) = your R will be a decimal, I will assume you know...

pre-calculus math
a zero of 3 gives us a factor of (x-3) complex zeros always come in conjugate pairs, so if -3-2i is one of them, -3+2i must be another. factors are (x - (-3-2i)) and (x - (-3+2i)) or (x + 3 + 2i) and (x + 3 - 2i) multiply the last two to get a quadratic factor (......) your f(...

Math
Thanks Steve, how sloppy of me

Math
amount of the 1% stuff to be added ---- x ounces .1x + .4(100) = .16(x + 100) solve for x

Algebra
f(2) = 21 , you had that f(a) = 6a^2 - 3 all you had to do is find the average rate of change, or more commonly known as the slope average rate of change = (6a^2 - 3 - 21)/(a - 2) = (6a^2 - 24)/(a-2) = 6(a^2 - 4)/(a-2) = 6(a+2)(a-2)/(a-2) = 6(a+2) , a ? 2

Math
1.6666666667 is NOT an irrational number. (1.6666666667 = 16666666667/10000000000 , there! I wrote it as a rational number)

Calculus
Your equation should have been h = -16t^2 - 6t + 130 When it hits the ground, h = 0 so, 16t^2 + 6t - 130 = 0 I would use the quadratic equation formula to solve for t (to be able to handle this topic, you MUST know that formula) make sure to reject any negative value of t.

Math
PV = 30,000 + 30,000( 1 - 1.0593^-12)/.0593 = ....

alg
y = 3x - 1 for (2,5) LS = 5 RS = 3(2) - 1 = 5

Algebra
I just googled : graph of a quadratic function, and guess what ? replace "quadratic" with the other two words

Advanced Algebra
I agree, but then pay this off as quickly as possible with such a high interest rate. Notice the payment of $25 wouldn't even pay the interest. (first months interest after introductory period = 1800(.2399)(1/12) = $35.99

1 Out Of 100 Math Trick HELP PLEASE!!!
1. Choose a number between 1 and 100. ------> x 2. Multiply the number by 5. -------> 5x 3. Add 15 to the number. -------> 5x+15 4. Divide the number by 5. ------> x+3 5. Subtract the original number. ------> 3 try it with any number: 1. ----- 12 2. ------ 60 3...

Pre-calc
Use brackets to write the fractions, such as 1/(2x) + 6/2 , <---- that was a guess, I can't tell what you meant

Pre-calc
I will assume that these are the zeros or the solutions to your function = 0 if 3-i is a zero, then 3+i is a zero, since complex solutions always appear in conjugate pairs sum of those roots = 6 product of those roots = 9 - i^2 = 10 so the quadratic producing those two complex...

Algebra
your formula is interpreted this way f(3) = f(2) + f(1) f(4) = f(3) + f(2) f(5) = f(4) + f(3) etc so f(3) = 3 + 2 = 5 f(4) = ....... notice we already eliminated b) continue .... btw, this is a famous sequence called the Fibonacci sequence, one of my favourite topics in Math.

Math
How did you possible get those answers ???

Algebra
What problem? Are you switching names ??

Algebra
No How did you get that ????

Math
remember , Perimeter = 2 x width + 2 x length area = length x width Perimeter = 2(5x-4) + 2(5x) = .... area = 5x(5x-4) = ... in each case simplify my expression

Pre-Calculus
To prove an identity, we usually start with one side and using basic identities show that it is equal to the other side LS = cosx - sex = cosx - 1/cosx = (cos^2 x - 1)/cosx = - sin^2 x / cosx = -sinx(sinx/cosx) = -sinx tanx = RS

Math
Didn't you want to make at least $200 ? So it should be 15h ? 200 h ? 40/3 , not less than like you had However, your conclusion that the painter must work a minimum of 13 and 1/3 hours to earn at least $200, is correct

Math
correct,

Algebra 2
depends on the transformation. e.g. suppose we have f: (x,y) ----> (x,-y) , a reflection in the x-axis , and g: (x,y) ---> (-x,-y) , a reflection in the origin if we do fg (x,y) ---> (x,-y) ---> (-x,y) and if we do gf (x,y) = (-x,-y) ---> (-x,y) , we get the ...

math
explain the meaning of 127nine

algebra
| 4x - 5 | > 4 4x - 5 > 4 OR -4x + 5 > 4 4x > 9 or -4x > -1 x > 9/4 or x < 1/4 change into the notation you learned and graph on a number line

algebra 2
6x-8 = 4 or -6x+8 = 4 6x = 12 or -6x = -4 x = 2 or x = 2/3

algebra
follow the same steps and procedure as in https://www.jiskha.com/display.cgi?id=1506548306 except use AND between the two inequations

algebra 2
width --- x length --- 2x perimeter = 2width + 2 lengths = 54 continue

algebra
Both conditions are referenced in terms of nickels, so let the number of nickels be x number of dimes = x+1 number of pennies = x+6 Value equation: 5x + 10(x+1) + x+6 = 480 continue ....

Algebra 2 A
correct make sure your equation is 26.00+3.25x=24.00+3.50x

maths
Ummmhh, if you are half as old as your sister, wouldn't your sister be twice as old?? . I defined it the way I did to avoid fractions. What does 6(x-20) mean? Does it not say 6 times (the son's age) ?? 2x-20 = 6(x-20) 2x-20 = 6x - 120 -4x = -100 x = 25 So the son is ...

maths
So the father is now twice as old as his son son's age ---- x father's age ---- 2x Twenty years ago : son's age = x-20 father's age = 2x-20 2x-20 = 6(x-20) solve for x, etc

math
first of all , you have a typo in g(x)=x^2=7x I think you meant: g(x)=x^2+7x , since the + and the = are on the same key you are given that g(x) = x^2 + 7x so you want g(3). As Philip stated, wherever you had an x , now put in a 3 g(3) = 3^2 + 7(3) = 9 + 21 = 90 so since f(x...

College Algebra: Please Help Me. Thanks.
f(x)=4x^2+3x+5 and g(x)=3x^2+2x+2 I will do A and C, you do the rest a) (f+g)----> 7x^2 + 5x + 7 (f+g)(3) = 7(3)^2 + 5(3) + 7 = 63 + 15 + 7 = 85 c) (f-g)(x) = 4x^2+3x+5 - (3x^2+2x+2) = x^2 + x + 3

Math
a) h = 8 + 6t 6t = h-8 t = (h-8)/6 c) when t = 6 h = 8 + 6(6) = .... d) when h = 29 29 = 8 + 6t 21 = 6t t = 21/6 = 3.5 it would take 3.5 months

PRE-CALC
you are given that x = i is a solution Complex roots, just like irrational roots, always come in conjugate pairs, so x = -i is another solution so you know (x+i) and (x-i) are factors (x+1)(x-1) = x^2 + 1 which means x^2 + 1 is factor of your given polynomial now do a long ...

8th grade Math Connections Academy
#5 25 is a perfect square ---- 5^2 = 25 , but 27 is a perfect cube --- 3^3 = 27 #6 is incorrect ?9 - 7 = 3-7 = -4, which is an integer Whole numbers are positive integers I agree with the others.

Math
24.4 trillion = 24,400,000,000,000 cost per person = 24,400,000,000,000/325,000,000 = 24,400,000/325 = $62,769 At $62 it could be paid off in 1 year by everybody chipping in a bit, unfortunately .....

Math
number dogs = 135(.365)(1.6) = appr 78.8 million dogs

math
-8y+3(g+h) - -5y-4(g+h) = -8y + 3g + 3h + 5y - 4g - 4h = ..... btw, - - 5 is considered "poor mathematical form"

Maths
I drew a horizontal flight path 400 m above the ground. On that path, I labeled the first position of the plane as A and the 2nd position as B, and the location of Melbourne on the ground as M I also labeled C on the flight path as the point directly above M. Let the speed of ...

math
3150 = 9*25*14 you take it from here

9th Grade Math
yes

9th Grade Math
none are correct A typical equation of a straight line, other than vertical or horizontal lines, need an x and a y variable. I will do one of them , say #4, you do the others slope of line = (-10-2)/(15-5) = -12/10 = -6/5 using the point (5,2), y - 2 = (-6/5)(x-5) multiply ...

Calculus
Let the vertex on the line 3x + 4y = 12 be (x,y) then y = (12-3x)/4 = 3- 3x/4 area = xy = x(3 - 3x/4) = 3x - 3x^2 /4 d(area)/dx = 3 - (3/2)x = 0 for a max of area (3/2)x = 3 3x = 6 x = 2 , y = 3 - 6/4 = 3/2 max area = xy = 2(3/2) = 3 units^2

math Please help!!
look at your list of properties, which pattern do you see?

math Please help!!
one has square brackets around it, and the other one doesn't. I would consider both to be -3

algebra
each of the equal angles ---- x third angle = 2x - 4 so : x + x + 2x-4 = 180 continue

Algebra
now: son's age --- x man's age --- 3x 5 years ago: son's age = x-5 man's age = 3x-5 3x-5 = 4(x-5) solve and the mystery will be unravelled.

math
just solve the two equations. I would use y = 20-x from the first and sub it into the 2nd let me know what you get

math
Here is just one such worksheet http://www.bearsdenacademy.e-dunbarton.sch.uk/_includes/attachments/P1283/Unit2_TrigonometricEquations.pdf That should keep you busy for a while. Try the questions before looking at the solutions.

math
Your first source would be your textbook. Perhaps your teacher gave you a handout of such equations. You can always google "trig equations" or "trig equations worksheet" There would be an infinite number of such equations.

maths
time in car ---- t hrs time on motorcycle --- 1 - t hrs 30t + 18(1 - t) = 22 solve for t, sub into 30t to get the distance in km

Math
width --- w length --- 3w 2(w+3w) = 96 4w = 48 w = 12 m or 1200 cm 3w = 36 m or 3600 cm area of flower bed = 1200(3600) cm^2 area of rectangle including path = (1280)(3680) cm^2 area of walkway = the difference or 390400 cm^2 volume of concrete needed for walk = 390400(15) cm^...

algebra
5x - 3y = 0 5x = 3y or 3y = 5x y = (5/3)x , which is in the form of y = mx, a direct variation.

Math
The areas of two similar figures area proportional to the square of their corresponding sides, so w^2/18^2 = 52/117 w^2 = 144 w = ?144 = 12

Physics/Math
You must be studying vectors in 3-D and cos ?, cos ?, and cos ? must be the direction cosines of a vector <a, b, c> you will recall that cos ? = a/?(a^2 + b^2 + c^2) cos ? = b/?(a^2 + b^2 + c^2) cos ? = c/?(a^2 + b^2 + c^2) Here is a great youtube which uses a specific ...

maths
What happened to the 100 ml that were split ? If they were given as part of the share , why not just do 2500 ml ÷ 4 = 625 ml per child or 100 ml ÷4 = 25 ml remaining 2400 ml ÷ 4 = 600 ml, and of course 600 ml + 25 ml = 625 ml , same as above

Math
Where are points a and b on the pond? What is a mosese ?

Further maths
Let x be the number who passed both. x + 31-x + 29-x + 3 = 50 -x = -13 x = 13 number who passed Chemistry only = 31-x = 31-13 = 18

Math
In most languages, there are special words for very common numerical values, as well as mathematical concepts e.g. almost every language has a special word for 12 besides the numerical name. That is, in English we use "dozen" meaning 12, in German "Dutzend"...

math
translating your conditions: W = k * w* h^2 / l given: w = 3in, h = 4in, l = 6 ft or 72 in , W = 28 tons 28 = k(3)(16)/72 k = 42 W = 42 * w* h^2 / l plugging in the second case: W = 42(5)(16)/240 = 14 tons

Algebra 2
6|6-4x|=8x+4 divide by 6 |6-4x|=(8x+4)/6 ---- I wanted to isolate the absolute value expression 6-4x = (8x+4)/6 OR 6-4x = -(8x+4)/6 36-24x = 8x+4 or 36-24x = -8x - 4 -32x = -32 or -16x = -40 x = 1 or x = 40/16 = 5/2 I will leave it up to you to verify my answers

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