С1. =1/9a^4 -2*1/3a²*1/4b² +1/16b^4 - -1/9a^4 +1/16b^4= -1/6a²b² +1/16b^4 +1/16b^4 = 2/16b^4 -1/6a²b²= 1/8b^4 -1/6a²b²= 1/2b²(1/4b² -1/3a²)
B1. (3x-2)(3x+2)=9х²-4
(2x+1)²=4х²+4x+1
(5x-1)(x+2)=5х²+9x-2
9х²-4-4х²-4x-1-5х²-10x+x+2=23
-5-4x-9x+2=23
-13x-3=23, -13x=26, x= -2