1,678 reputation
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age 19
visits member for 3 years, 9 months
seen 15 hours ago

Sep
20
asked Proving that $\lim_{x\to3}\frac{x}{4x-9}=1$
Sep
20
asked Why is $|(x-2)| < \delta \le 1$ true when proving $\lim_{x\to2}(3x^2-x)=10$?
Sep
19
comment Proving $\lim_{x\to1}(x^2+3)=4$
Hm I'm not very sure how can $|x-1| < \delta$ lead to $|x+1|\le 3$. If you increase $|x-1|$ by $2$ to reach $|x+1|$, shouldn't it be $|x+1| \le 2$ rather than $3$?
Sep
19
accepted Proving $\lim_{x\to1}(x^2+3)=4$
Sep
19
comment Why does $|x-1|^2+3|x-1| < \epsilon \implies |x-1|^2 < \frac{\epsilon}{2} \ \ \land \ \ 3|x-1| < \frac{\epsilon}{2}$?
@Oleg567: What if $a = b = \epsilon/2$?
Sep
19
asked Why does $|x-1|^2+3|x-1| < \epsilon \implies |x-1|^2 < \frac{\epsilon}{2} \ \ \land \ \ 3|x-1| < \frac{\epsilon}{2}$?
Sep
19
asked Proving $\lim_{x\to1}(x^2+3)=4$
Sep
12
asked Determinant of a matrix with trigonometry functions.
Sep
7
asked Determining what values in a system can cause infinite/unique/no solutions.
Sep
7
comment For what values of $p$ and $b$ is the vector $(b,8,b+7)$ a solution of this system?
Thanks, that's right (although $b$ yields $-5$).
Sep
7
accepted For what values of $p$ and $b$ is the vector $(b,8,b+7)$ a solution of this system?
Sep
7
comment For what values of $p$ and $b$ is the vector $(b,8,b+7)$ a solution of this system?
@Adriano: Huh, it seems it should be $b = -5$. The exercise's answer seems to be wrong haha.
Sep
7
revised For what values of $p$ and $b$ is the vector $(b,8,b+7)$ a solution of this system?
added 1 character in body
Sep
7
asked For what values of $p$ and $b$ is the vector $(b,8,b+7)$ a solution of this system?
Sep
5
accepted Determining the values of $b$ in $Ax=b$ to have a consistent system.
Sep
5
asked Determining the values of $b$ in $Ax=b$ to have a consistent system.
Sep
1
accepted Is $A$ invertible if $ABAB^2 = I$?
Sep
1
comment Is $A$ invertible if $ABAB^2 = I$?
Only of the same size?
Sep
1
asked Is $A$ invertible if $ABAB^2 = I$?
Sep
1
asked Why does a matrix column being a multiple of another imply that the matrix is singular?