You can definitely multiply 2x2 matrices with each other. In fact you can multiply a AxB matrix with a BxC matrix, where A, B, and C are natural numbers. That is, the number of columns of the first matrix must equal the number of rows of the second matrix--we call this "inner dimensions must match."
I do not. I f*cking hate matrices. I multiply sheep.
I assume since you're asking if 2x2 invertible matrices are a "subspace" that you are considering the set of all 2x2 matrices as a vector space (which it certainly is). In order for the set of 2x2 invertible matrices to be a subspace of the set of all 2x2 matrices, it must be closed under addition and scalar multiplication. A 2x2 matrix is invertible if and only if its determinant is nonzero. When multiplied by a scalar (let's call it c), the determinant of a 2x2 matrix will be multiplied by c^2 since the determinant is linear in each row (two rows -> two factors of c). If the determinant was nonzero to begin with c^2 times the determinant will be nonzero, so an invertible matrix multiplied by a scalar will remain invertible. Therefore the set of all 2x2 invertible matrices is closed under scalar multiplication. However, this set is not closed under addition. Consider the matrices {[1 0], [0 1]} and {[-1 0], [0 -1]}. Both are invertible (in this case, they are both their own inverses). However, their sum is {[0 0], [0 0]}, which is not invertible because its determinant is 0. In conclusion, the set of invertible 2x2 matrices is not a subspace of the set of all 2x2 matrices because it is not closed under addition.
how to multiply two sparse matrices
No. Multiplication of matrices is, in general, non-commutative, due to the way multiplication is defined.
a,b,c,d,
Multiply matrices
4
Multiply matrices
1 1/2X2 =3
it means you multiply 2x2
because when you multiply 2x2 it =4 then you multiply 4x3=12 then you multiply 12x7=wich you will have your answer 84!
The inverse of a 2x2 matrix:[a b][c d]is given by__1___[d -b]ad - bc [-c a]ad - bc is the determinant of the matrix; if this is 0 the matrix has no inverse.The inverse of a 2x2 matrix is also a 2x2 matrix.The browser used here is not really suitable to give details of the inverse of a general matrix.Non-singular square matrices have inverses and they can always be found. Singular, or non-square matrices do not have a proper inverses but canonical inverses for these do exist.