The mathematical relationship that follows were formulated by an operations research analyst at the smith-lawton chemical company. Which ones are invalid for use in a linear problem and why?

A) maximize profit= 4x1 + 3x1x2 + 8x2 + 5x3 subject to

b. 2x1+x2=2x3

c. x1 - 4x1 >or= 6

d. 1.5xsquared +6x2 + 3x3 >orequal to 2

E. 119x2 - 0.35x3 =175

f. x1 + 4x2 + 3 squareroot x3

g. -x1-x2 + x3=5