Thread: Math again? Google isn't helpful

Amiright?

Find the intervals on the real number lin for which the radicand is nonnegative(greater than or equal to zero).

1. Sqrt(x-5)

2. (7-2x)^(1/4)

I don't understand the question...but my answers are this.
1. X>5

2. X<3.5 or X<7/2

I have no idea what a 'radican' is, but they seem right, except that those less than or equal to and more than or equal to signs need to be just less than and more than signs. The expressions equal to zero for X=5 and X=3.5 respectively, and are undefined over the reals for X less than those (but still defined over the complex numbers).

Originally Posted by archdreamer

I have no idea what a 'radican' is, but they seem right, except that those less than or equal to and more than or equal to signs need to be just less than and more than signs. The expressions equal to zero for X=5 and X=3.5 respectively, and are undefined over the reals for X less than those (but still defined over the complex numbers).

Sorry I meant to type Radicand. A radicand is any number under the radical such as The symbol √ used to indicate the square root or nth root.

I think they need to be greater/less than or equal to because the actual equation (based on the question posed before the equation) is...

√(x-5)>0

Oh wait I think I get what you're saying.

Originally Posted by archdreamer

I have no idea what a 'radican' is, but they seem right, except that those less than or equal to and more than or equal to signs need to be just less than and more than signs. The expressions equal to zero for X=5 and X=3.5 respectively, and are undefined over the reals for X less than those (but still defined over the complex numbers).

Wrong. He requires greater than or equal to zero, so the signs require equality as well. Your comment about real versus imaginary is correct but quite irrelevant to the problem as stated.

Sandform: Did you edit your post? I could have sworn it said 'greater than zero'. Oh well, what drew says is correct, if we are trying to solve √(x-5)>0 for x.

Your answers are correct:

x-5>o
x>5

Pretend thats got a line under it.

(7-2x)(1/4)>o
28-8x>o
28>8x
28/8>x
14/4
7/2
3.5

And hell, I don't even have to worry about maths again. Life is good

I, on the other hand, am about to begin third year university math. I'm gonna be finding so many eigenvectors that I'll be speaking German by April.

I, on the other hand, am about to begin third year university math. I'm gonna be finding so many eigenvectors that I'll be speaking German by April

I thought you did Physics?

I hate working out eigenvalues.

Yeah, especially when you're jumping into partial differential equations and real analysis and other goodies...

I thought first year was real analysis? Not the third year. LOL.

Sandform, does you're anwser agree with the book?

I hate partial differential equations, the worst thing ever. I hate intergration, because differentiation is soo easy.

Originally Posted by wendylove

I thought you did Physics?

I do do physics, but my major is math.

Originally Posted by wendylove

I thought first year was real analysis? Not the third year. LOL.

Uh, no. I'm talking about Lebesgue integrals and proofs of stuff. Way way above first year.

Originally Posted by wendylove

I hate partial differential equations, the worst thing ever. I hate intergration, because differentiation is soo easy.

Spoken like a true first year.

Originally Posted by wendylove

Sandform, does you're anwser agree with the book?

I wasn't issued a book sadly. Nor did my teacher give us notes hehe. She expects us to know this already, which is reasonable, considering it is basic algebra and I'm taking calculus.

Ok, here's a more challenging one:

x^2 - x -6 >=0

Hint: You might want to draw the function to get your bearings, otherwise it might be difficult to come up with the full answer.

Originally Posted by drewmandan

Ok, here's a more challenging one:

x^2 - x -6 >=0

Hint: You might want to draw the function to get your bearings, otherwise it might be difficult to come up with the full answer.

You talking to me?

Spoiler for answer:

(1+-√(1-4*1*-6)) / 2
(1 +- √(25)) /2
(1 +- 5) / 2
-4 / 2 = -2
6 / 2 = 3

x = -2
x = 3

Lets turn this into a math game in which the next question is harder than the last...and you have to show your work.

Here's a more challenging one.

√(3x-2) = 4 - x

Originally Posted by Sandform

You talking to me?

Spoiler for answer:

(1+-√(1-4*1*-6)) / 2
(1 +- √(25)) /2
(1 +- 5) / 2
-4 / 2 = -2
6 / 2 = 3

x = -2
x = 3

This is precisely why I suggested you draw the function. Your answer is incomplete.

Originally Posted by Sandform

Lets turn this into a math game in which the next question is harder than the last...and you have to show your work.

Here's a more challenging one.

√(3x-2) = 4 - x

Yuck.

√(3x-2) = 4 - x
3x -2 = 16 - 8x + x^2
x^2 - 11x +18 =0

x= (11 &#177; √(121-72))/2
x = 11/2 &#177; 7/2
x = 9, x = 2

edited for stupidy

Here's my response!

x^3 + 6x^2 +11x +6 >= 0

Let the "tricate" of a number x be defined as one third of the smallest multiple of 3 greater than x. If the tricate of z is 3, which of the following could be the value of z?

Fun sat prep question...lolz.

If you have never been exposed to this type of question before you get duped into not realizing that tricate isn't a real term.

Forgot to add...

answer choices:

a 2
b 5
c 7
d 9
e 11

Easy. 7. Gawd, American students get dumber by the year.

Originally Posted by drewmandan

Easy. 7. Gawd, American students get dumber by the year.

Excuse me...how can you state the "dumbness" of a person...did I say I(or any other student) didn't know how to do it? It is just an SAT prep question...who says we don't know how to do it you condescending asshole...

Originally Posted by Sandform

Excuse me...how can you state the "dumbness" of a person...did I say I didn't know how to do it? It is just an SAT prep question...who says we don't know how to do it you condescending asshole...

The fact that this question is being given to high school students when I could have easily done it at age 10 speaks volumes about the lax standards of the American public school system. I don't know where you sit on the scale, but I can guarantee you that you will be in a HUGE shock when you begin university, if you go on to study a science.

Originally Posted by drewmandan

The fact that this question is being given to high school students when I could have easily done it at age 10 speaks volumes about the lax standards of the American public school system. I don't know where you sit on the scale, but I can guarantee you that you will be in a HUGE shock when you begin university, if you go on to study a science.

Ah, I see where the misconception is coming from then.

I don't think you understand the nature of the SAT...

The SAT is designed to show your knowledge over general skills.

This means that questions are over high levels of knowledge and low levels of knowledge.

There are four sections for SAT math.

Three sections for writing, and three sections for reading.

The purpose of that question was to see if you could understand the question...solving it would be rather easy after.

I have no doubt that at 10 if someone explained to you what the question was asking you could have figured it out...but I do have sincere doubts that you would have understood the question as given.

Once you understand the question, the answer becomes obvious...I personally find it rather easy too, but it isn't the hardest question on the SAT...


The problem faced with the SAT is the fact that for math they can't give you truly complex questions...questions that require an entire board or 3 pieces of paper to solve. You get roughly 25 minutes to answer 25 questions...


What kind of test do they have in Ontario/Canada?

It should be noted...this isn't the equivalent of an end of the year exam over the class you have been studying all year...Generally the level of difficulty for these tests are based on what class you are taking...