arooj1a2b3c

If (x + y) (x^2 - y^2) = 0 , which of the following must be true?
(A) x = y
(B) x = -y
(C) x^2 = y^2
(D) x^2 = -y^2
(E) x^3 = x^3

C is the correct answer, but what makes B more incorrect than C? This was the final question on section 2 of the 2006 Saturday PSAT.

rspence

B is incorrect because x could equal y, therefore B does not have to be true. Here, x^2 = y^2, or x = +/- y, answer is C.

SalmaThabet

a train started at station s and has been traveling r miles per hour for t hours in terms of r and t ,how many miles from station had the train travled 3t/4 hours ago ? the answers is (E) i cannot understand why it is e

HarveyMuddLove

^ would be helpful to list answer choices, (esp. E).

I assume the answer goes something like this: at 3t/4 hours ago, the train has traveled for t-3t/4 or t/4 hours, so distance = rate * time, so distance = r * t/4 = rt/4 miles from station.

SalmaThabet

thanks for your help

SalmaThabet

three children each weight 100 pounds or less their averge (arithmetic mean ) weight is 80 pounds if one of them weighs 80 pounds , what is the least possible weight , in pounds,of a child in the group? the answers is 60

Niquii77

Explanation:
The total of their weights are 240. [(x+y+z)/3=80]->[x+y+z=240]
One of the kids weigh 80 lbs. [240-80=160]
Find the smallest number x could be. [160-100=60]{The largest weight a child could be} Gives you the smallest weight.

60 lbs.

younha

If a-x =12, b-y=7, c-z=15, and a+b+c=50, then x+y+z=?

Answer is 16. How do you solve this?

Please and thank you!

Niquii77

It's plain old substitution:a=12+x b=7+y c=15+z

Plug it into a+b+c=50
(12+x)+(7+y)+(15+z)=50
Then you get:
x+y+z=16

SalmaThabet

a-x=12 then a=12+x ,b-y=7 then b=7+y and c-z=15 then c=15+z , 12+x+7+y+15+c=50
12+7+15=34
34+x+y+z=50
x+y+z=50-34=16

SalmaThabet

1)a person paid atotal of $700 for shirts priced at $ 9 and $ 13 each if the person purchased two $ 13 shirts for every $ 9 shirt , what was the total number of shirts purchased?
2)if 1 jar +5 cups =1 tub and if 3 jars +2 cups =2 tubs, how many cups equal a tub ?
the answers of the first 60 and the secound 13

SalmaThabet

i know the secound question please help me to solve the first

HarveyMuddLove

let a = $9 shirts, then there are 2a $13 shirts because he bought two $13 shirts for each $9 shirt

13(2)a + 9a = 700
35a = 700
a = 20

TOTAL SHIRTS = a + (2)a = 3a = 60

younha

Thanks for the help! Greatly appreciated!!

SalmaThabet

in a discount clothing store, Billie bought 4 pairs of socks at x dollars per pair and 3 shirts at 3x dollars each. if the total cost of the socks and shirts was $ 19.50, what was the cost, in dollars,of one shirts ? the answer is 450