а) х<span>^4+х<span>^2+х^2+2=х^4+2х^2+2</span></span>
б) а^5-a^2-a^3+1
в) 3b^3-12+3b^4-12b
<span>г) 2y^4+4y^2-30y^2-60=2y^4-26y^2-60</span>
(0.2)^3+a^3=0.008+a^3
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(0.2)^3+a^3=0.008+a^3=(0.2+a)(0.04-0.2a+a^2)
=4а^2-20а+25-3а^2+6а=а^2-14а+25