Toán Lớp 7: Tìm x:
-2/3 : x +5/8= -7/12
(2 . x + 3)^2=25
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Toán Lớp 7: Tìm x:
-2/3 : x +5/8= -7/12
(2 . x + 3)^2=25
Comments ( 2 )
text{Giải đáp + Lời giải và giải thích chi tiết :}
-2/3 : x + 5/8 = -7/12
=> -192 = -21(8x + 5)
=> -21(8x + 5) = -192
=> 8x + 5 = -192 : -21
=> 8x + 5 = 64/7
=> 8x = 64/7 – 5
=> 8x = 29/7
=> 8x = 29/7 : 8
=> x = 29/56 .
________________________
(2 . x + 3)^2 = 25
<=> 2x + 3 = \sqrt{25}
<=> 2x + 3 = -\sqrt{25}
=> x ∈ {1 ;-4} .
text{#ShuOwO}
Answer
-2/3 : x + 5/8 = -7/12
=> -2/3 : x = -7/12 – 5/8
=> -2/3 : x = -29/24
=> x = -2/3 : {-29}/24
=> x = 16/29
Vậy x = 16/29
_______________________
(2x + 3)^2 = 25
=> (2x + 3)^2 = (+-5)^2
=> 2x + 3 = +-5
=> [(2x + 3 = 5),(2x + 3 = -5):}
=> [(2x = 5 – 3),(2x = -5 – 3):}
=> [(2x = 2),(2x = -8):}
=> [(x = 2 : 2),(x = -8 : 2):}
=> [(x = 1),(x = -4):}
Vậy x \in {1 ; -4}