274.

9 √3−9 ₺5+3 √16875−15+5 V675—5 √25.

6

15

278.

a-b

√313+3°. √52+ √3o. V5++675 + √33. √50 + √5TM°.

19058

279. 17—12 √2+12 V3+8 V9−26 V72.

298. x=ac+bd; y=ad-bc.

296. The former is possible, the latter impossible.

299. a―d+(b−c) -1, and a-d-(b−c) √—I.