1  (х-у)(х+у)

2 (с-d)(c+d)

3 (e-f)(e+f)

4 (g-h)(g+h)

5 (m-k)(m+k)

6 (3a-4b)(3a+4b)

7 (5x-6)(5x+6)

8 (8-7y)(8+7y)

9 (9q-10p)(9q+10p)

10 (13s-12r)(13s+12r)

11 (0.1-x)(0.1+x))

12 (0.2-y)(0.2+y)

13 (0.3-a)(0.3+a)

14 (b²-0.4)(b²+0.4)

15 (0.5x²-0.6y)(0.5x²+0.6y)

16 (0.7a³-1.2b)(0.7a³+1.2b)

17 (1.3x-1.4y⁴)(1.3x+1.4y⁴)

18 (1.5x²-1.6p²)(1.5x²+1.6p)=(√1.5x-√1.6y)(√1.5x+√1.6y)(1.5x²+1.6p)

19 (2.7x³-2.8y³)(2.7x³+2.8y³)

20 (3.4a⁴-3.1b⁵) (3.4a⁴+3.1b⁵)