Toán Lớp 6: Bài 1: Tìm x :
a) (7x – 15): 3 = 9
b) 71 + (x – 16:2²) = 75
c) [43 – (56 – x)].12 = 384
d) (5 + x)ᒾ – 36 = 0
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Toán Lớp 6: Bài 1: Tìm x :
a) (7x – 15): 3 = 9
b) 71 + (x – 16:2²) = 75
c) [43 – (56 – x)].12 = 384
d) (5 + x)ᒾ – 36 = 0
Giải từng bước giúp em với
Comments ( 2 )
a) (7x – 15) : 3 = 9
7x – 15 = 9 . 3
7x – 15 = 27
7x = 27 + 15
7x = 42
x = 42 : 7
x = 6.
b) 71 + (x – 16 : 2²) = 75
71 + (x – 16 : 4) = 75
71 + (x – 4) = 75
x – 4 = 75 – 71
x – 4 = 4
x = 4 + 4
x = 8.
c) [43 – (56 – x)] . 12 = 384
43 – (56 – x) = 384 : 12
43 – (56 – x) = 32
56 – x = 43 – 32
56 – x = 11
x = 56 – 11
x = 45.
d) (5 + x)² – 36 = 0
(5 + x)² = 0 + 36
(5 + x)² = 36
→ 5 + x ∈ {6; -6}.
→ x ∈ {1; -11}.
Bài 1:
a) (7x – 15): 3 = 9
7x – 15 = 9 . 3
7x = 27 + 15
x = 42 : 7
x = 6
b) 71 + (x – 16:2²) = 75
x – 16: 4 = 75 – 71
x – 4 = 4
x = 4 + 4
x = 8
c) [43 – (56 – x)].12 = 384
43 – (56 – x) = 384 : 12
43 – (56 – x) = 32
56 – x = 43 – 32
56 – x = 11
x = 56 – 11
x = 45
d) (5 + x)ᒾ – 36 = 0
(5 + x)ᒾ = 36
(5 + x)ᒾ = (± 6)ᒾ
TH1: 5 + x = 6
x = 6 – 5
x = 1
TH2: 5 + x = -6
x = -6 – 5
x = -11
Vậy x ∈ { 1; -11}