Write the following set of equations in matrix form:
[ 5x³ - 6x² 2x² 7x³ = 50 0 x₁ - 7x₃ ]
a) (x = 2 -1 7 )
b) (x = 1 0 -1 )
c) (x = -3 5 2 )
d) (x = 4 2 -3 )