![-a^2=(-1)\cdot a\cdot a](https://tex.z-dn.net/?f=-a%5E2%3D%28-1%29%5Ccdot%20a%5Ccdot%20a)
Regardless of the sign of
![a](https://tex.z-dn.net/?f=a)
, we have
![a\cdot a=a^2\ge0](https://tex.z-dn.net/?f=a%5Ccdot%20a%3Da%5E2%5Cge0)
(never negative). But multiplying by -1 makes it negative.
On the other hand,
![(-a)^2=((-1)\cdot a)^2=(-1)^2\cdot a^2=1\cdot a^2=a^2](https://tex.z-dn.net/?f=%28-a%29%5E2%3D%28%28-1%29%5Ccdot%20a%29%5E2%3D%28-1%29%5E2%5Ccdot%20a%5E2%3D1%5Ccdot%20a%5E2%3Da%5E2)
which can never be negative for real
![a](https://tex.z-dn.net/?f=a)
.
Answer:
cos(m∠B) = 2√5/5
Step-by-step explanation:
Easiest way is to guess and check on this problem. When you take the cos(m∠B), you would get 6/3√5, rationalized to 2√5/5. That would be the correct answer.
you can measure the first angle with a protractor and then measure the other one see if there is a different angle
Answer:
![\huge\boxed{Que \ es \ un \ variable \ ?\hookleftarrow}](https://tex.z-dn.net/?f=%5Chuge%5Cboxed%7BQue%20%5C%20es%20%5C%20un%20%5C%20%20variable%20%5C%20%3F%5Chookleftarrow%7D)
✐ En matemáticas, una variable es un símbolo que funciona como marcador de posición para expresiones o cantidades que pueden variar o cambiar; se utiliza a menudo para representar el argumento de una función o un elemento arbitrario de un conjunto. Además de los números, las variables se utilizan comúnmente para representar vectores, matrices y funciones.