If A=`[[4,8],[-2,-4]]`,prove that `A^2`=0

Prove that: 2xx^7C_4=^8C_4

If A=[ (3,-2),( 4 ,-2) ] and I=[(1,0),(0,1)] , then prove that A^2-A+2I=O .

If A=1/9[-8 1 4 4 4 7 1-8 4] , prove that A^(-1)=A^T .

If A= (1)/(9) ((-8,1,4),(4,4,7),(1,-8,4)) , prove that, A^(-1)= A^(T) . Hence solve the following system of equations: -8x + y + 4z= 0, 4x + 4y + 7z= 18, x- 8y + 4z= 9

In DeltaABC , a=3,b=4,c=2, then prove that: cosA/2 = (3sqrt(6))/(8)

In DeltaABC , if a = 2, b = 3, c = 4, prove that cosA=7/8 .

In DeltaABC , a=9,b=8 and c=4, prove that: cosB-2cosC=-4/3

if A = [[3,9,0],[1,8,-2]] and B = [[4,0,2],[7,1,4]] find A+B and A-B?

If z= -3 + sqrt2i , then prove that z^(4) + 5z^(3) + 8z^(2) + 7z + 4 is equal to -29

If an infinite G.P. has 2nd term x and its sum is 4, then prove that xin(-8,1]-{0}