4.(4)y'=[(x²-1)³]'+1'=3(x²-1)²·(x²-1)'+0=3(x²-1)²·2x=6x(x²-1)²y''=6x'·(x²-1)²+6x·[(x²-1)²]'=6(x²-1)²+6x·2(x²-1)·(x²-1)'=6(x²-1)²+6x·2(x²-1)·2x=30x⁴-36x²+6
