A² + 2ab + b² = (a + b)², a<span>² - 2ab + b² = (a - b)²</span>
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1) x</span>² + 8x + 16 = (x + 4)²<span>
2) b</span>² <span>+ 10b + 25 = (b + 5)</span>²<span>
3) a</span>² + 16a + 64 = <span> (a + 8)</span>²<span>
4) a</span>² - 14a + 49 = (a - 7)²<span>
5) x</span>² - 1.2x + 0.36 = (x - 0.6)²
6) y² + 1.8y + 0.81 = (y + 0.9)<span>²</span>
Vot i vse )) proshe prostogo)
1)D = (-10)ˇ2- 4.1.21=100-84=16
2a)(7x+1)ˇ2=0, 7x+1=0, x=-1/7 (dvuxkpatnyj koren)
b) V R neimeet uravnenie rešenie.
3)xˇ2-10x+21=0,(x-3)(x-7)=0,a)x-3=0,x=3,b)x-7=0,x=7