The quadratic equation with one variable has two real roots, namely the discriminant B2-4ac >；; 0

Namely: [3(a- 1)]2-4×2×(a2-4a-7)

=9a2- 18a+9-8a2+32a+56

= a2+ 14a+65 = a2+ 14a+49+ 16

=(a+7)2+ 16

(a+7)2≥0

∴(a+7)2+ 16>； 0

No matter what the value of a is, equation 2x? +3(a- 1)x+a？ -4a-7=0 must have two unequal real roots.