1) a³-(b+1)³=(a-(b+1))(a²+a(b+1)+(b+1)²)=(a-b+1)(a²+ab+a+b²+2b+1)
2)(a-1)³+(b+1)³=a³-3a²+3a-1+b³+3b²+3b+1=a³+b³-3a²+3b²+3a+3b=(a+b)(a²-ab+b²)-3(a²-b²)+3(a+b)=(a+b)(a²-ab+b²)-3(a-b)(a+b)+3(a+b)=(a+b)(a²-ab+b²-3(a-b)+3)=(a+b)(a²+b²-ab-3a+3b+3)
3) 5a³+5b³-3a²+3b²=5(a³+b³)-3(a²-b²)=5(a+b)(a²-ab+b²)-3(a-b)(a+b)=(a+b)(5(a²-ab+b²)-3(a-b))=(a+b)(5a²+5ab+5b²-3a+3b)
4) 16x³+54y³=2(8x³+27y³)=2(2x+3y)(4x²-6xy+9y²)
5) 8a³-b³+4a²+2ab+b²=(2a-b)(4a²+2ab+b²)+4a²+2ab+b²=(2a-b+1)(4a²+2ab+b²)
6a/7c - (36a²+49c²)/42ac + (7c-36a)/6a=
= 6a*6a/42ac -(36a²+49c²)/42ac + (7c-36a)*7c / 42ac =
(36a²-36a²-49c²+49c²-252ac) / 42ac=
=-252/42 = - 6
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7+14+21+28 и т.д. просто прибавляй по семь пока не дойдёшь до 150