<span>0,3(х-3)-0,5(6х-9)=0,3(14x-11)
0.3x-0.9-3x+4.5=4.2x-3.3
0.3x-3x-4.2x=-3.3+0.9-4.5
-6.9x=-6.9
x=-6.9 : (-6.9)
x=1
</span>
x^4-17x^2+16 = 0
t^2-17t+16 = 0
t= 16
t = 1
x^2 = 16
x^2 = 1
x = 4
x = –4
x = 1
x = –1
Ответ:
S14 = ((2 × 5 + 3 × (14 - 1))/2)×14 = 343
S24 = ((2 × 12 + 7 × (24 - 1))/2)×24=2220
S32 = ((2 × (-55) + 8 × (32-1))/2)×32 = 2208
S19 = ((2 × (-7,3) + 8 × (19-1))/2)×19=1229,3
Ну в параграфе в учебнике все подробно....