0,6X^2 + 0,8X - 7,8 = 0
6X^2 + 8X - 78 = 0
2 * ( 3X^2 + 4X - 39 ) = 0
D = 16 + 468 = 484 ; √ D = 22
X1 = ( - 4 + 22 ) : 6 = 3
X2 = ( - 4 - 22 ) : 6 = - 4 ( 1/3 )
C1.
ОДЗ:
1) x>0
2) x²-4≥0
(x-2)(x+2)≥0
x=2 x=-2
+ - +
------ -2 ------------
2 --------------\\\\\\\ \\\\\\\\\\\\\\\\
x∈(-∞; -2]U[2; +∞)
В итоге: x∈[2; +∞)
Решение неравенства:
log₃x -2=0
log₃x =2
x=3²
x=9
---------
-2-----------
2 -------------
9 -------------
Так как ОДЗ: х∈[2; +∞), то рассматриваем участок:
- +
-------
2 -------------- 9 -------------------
\\\\\\\\\\\\\\\\\
При х=3 log₃3 -2 =1-2= -1<0 (-) и
>0 (+)
При х=10 log₃10 -2>0 (+) и
>0 (+)
x∈[2; 9]
Ответ: [2; 9]
C2.
ОДЗ: х>0
4y²-11y+7=0
D=121-4*4*7=121-112=9
y₁=(11-3)/8=1
y₂=(11+3)/8=14/8=7/4
+ - +
--------
1 ---------- 7/4 --------------
\\\\\\\\\\\\
y∈[1; 7/4]
/////////////////////////////////////////////////////////////////
------ 0 --------
(1/5)^(7/4)------------ 1/5 -------------
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
x∈[
]
Ответ:
Объяснение:
!!!!!!!!!!!!!!!!!!!!!!!!!!
<span>(-10)^3+(-10)^2+(-10)^0 = </span>1000+100+1= -899