(************************************************************************) (* v * The Coq Proof Assistant / The Coq Development Team *) (* R) (x0 x1 : R), ((f x1 - f x0) * (1 / (x1 - x0)) + (g x1 - g x0) * (1 / (x1 - x0)))%R = ((f x1 + g x1 - (f x0 + g x0)) * (1 / (x1 - x0)))%R. Proof. intros. legacy field. Abort. (* Example 3 *) Goal forall a b : R, (1 / (a * b) * (1 / 1 / b))%R = (1 / a)%R. Proof. intros. legacy field. Abort. (* Example 4 *) Goal forall a b : R, a <> 0%R -> b <> 0%R -> (1 / (a * b) / 1 / b)%R = (1 / a)%R. Proof. intros. legacy field. Abort. (* Example 5 *) Goal forall a : R, 1%R = (1 * (1 / a) * a)%R. Proof. intros. legacy field. Abort. (* Example 6 *) Goal forall a b : R, b = (b * / a * a)%R. Proof. intros. legacy field. Abort. (* Example 7 *) Goal forall a b : R, b = (b * (1 / a) * a)%R. Proof. intros. legacy field. Abort. (* Example 8 *) Goal forall x y : R, (x * (1 / x + x / (x + y)))%R = (- (1 / y) * y * (- (x * (x / (x + y))) - 1))%R. Proof. intros. legacy field. Abort.