12 – 2.(-x + 3)2 = – 38 -20+3.(2x+1)3=-101 24/10/2021 Bởi Vivian 12 – 2.(-x + 3)2 = – 38 -20+3.(2x+1)3=-101
Đáp án: 12 – 2 . (-x + 3)² = -38 2 . (-x + 3)² = 12 – (-38) 2 . (-x + 3)² = 50 (-x + 3)² = 50 : 2 (-x + 3)² = 25 (-x + 3)² = 5² (-x + 3)² = (-5)² => $\left \{ {{-x+3=5} \atop {-x+3=-5}} \right.$ => $\left \{ {{-x=5-3} \atop {-x =-5-3}} \right.$ => \(\left[ \begin{array}{l}-x=2\\-x=-8\end{array} \right.\) => $\left \{ {{x=-2} \atop {x=8}} \right.$ Vậy x = -2 hoặc x = 8. -20 + 3 . (2x + 1) ³ = -101 3 . (2x + 1)³ = -101 – (-20) 3 . (2x + 1)³ = -81 (2x + 1)³ = -81 : 3 (2x + 1)³ = -27 (2x + 1)³ = (-3)³ => 2x + 1 = -3 2x = -3 – 1 2x = -4 x = -4 : 2 x = -2 Vậy x = -2. Chúc học tốt!!! Bình luận
Đáp án:
12 – 2 . (-x + 3)² = -38
2 . (-x + 3)² = 12 – (-38)
2 . (-x + 3)² = 50
(-x + 3)² = 50 : 2
(-x + 3)² = 25
(-x + 3)² = 5²
(-x + 3)² = (-5)²
=> $\left \{ {{-x+3=5} \atop {-x+3=-5}} \right.$
=> $\left \{ {{-x=5-3} \atop {-x =-5-3}} \right.$
=> \(\left[ \begin{array}{l}-x=2\\-x=-8\end{array} \right.\)
=> $\left \{ {{x=-2} \atop {x=8}} \right.$
Vậy x = -2 hoặc x = 8.
-20 + 3 . (2x + 1) ³ = -101
3 . (2x + 1)³ = -101 – (-20)
3 . (2x + 1)³ = -81
(2x + 1)³ = -81 : 3
(2x + 1)³ = -27
(2x + 1)³ = (-3)³
=> 2x + 1 = -3
2x = -3 – 1
2x = -4
x = -4 : 2
x = -2
Vậy x = -2.
Chúc học tốt!!!
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