x + x + x + x = 40
4x = 40
x = 40 : 4
x = 10
x + x + x + x = 40
hay x * 4 = 40
=> x = 40 : 4
=> x = 10
thử lại : 10 + 10 + 10 + 10 = 10 * 4 = 40
X+(x+1)+(x+2)+(x+3)+…+39+40=40
S = 1 + 1 x 2 + 2 x 3 + 3 ........... x 39 + 39 x 40 + 40
x⋮ 7 ; x⋮8 và < x < 100. TÌM x
Tìm x
30 + x = 40 + 60
10 + 90 = 40 + x
Tìm x
20 + x = 40 + 60
10 + 90 = 40 + x
tìm số tự nhiên x biết rằng 112⋮ x ,140⋮x và 10 < x <20
Tìm X
e) – 40 – (– 3 – 33) + (40 – x) = – (– 47) f) x(3x – 9). (121 – x2) = 0
g) – 62 – (38 + x) + 2x = – 100 h) (x + 1)2.(x2 + 1) = 0
i) (x – 12) – (2x + 31) = 6 k) 17/ (x + 3)3 : 3 – 1 = – 10
Tìm X
e) – 40 – (– 3 – 33) + (40 – x) = – (– 47) f) x(3x – 9). (121 – x2) = 0
g) – 62 – (38 + x) + 2x = – 100 h) (x + 1)2.(x2 + 1) = 0
i) (x – 12) – (2x + 31) = 6 k) 17/ (x + 3)3 : 3 – 1 = – 10
