Answer: 23 is a number.
Step-by-step explanation:
An algebraic expression is made up of terms consisting of variables (for example, n), a number (for example, 23) or a constant multiplied by variable or variables (for example, ax2 + bx + c).
For the first one the "-" makes what is in the parenthesis negative. Then the next step would be to combine like terms.
Answer:

Step-by-step explanation:
In order for the triangle to be a right one we need every side to be of the same length. see the photo for furyher explanation.
The correct answer is <u><em>(2,−1)</em></u>