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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Rút gọn các biểu thức sau: a. $2x.(2x-1)^{2}$ – $3x.(x+3).(x – 3)^{}$ – $4x. (x+1)^{2}$ b. $(a-b+c)^{2}$ – $(b-c)^{2}$ + $2ab^{}$

Home/ Toán Lớp 8: Rút gọn các biểu thức sau: a. $2x.(2x-1)^{2}$ – $3x.(x+3).(x – 3)^{}$ – $4x. (x+1)^{2}$ b. $(a-b+c)^{2}$ – $(b-c)^{2}$ + $2ab^{}$

Toán Lớp 8: Rút gọn các biểu thức sau: a. $2x.(2x-1)^{2}$ – $3x.(x+3).(x – 3)^{}$ – $4x. (x+1)^{2}$ b. $(a-b+c)^{2}$ – $(b-c)^{2}$ + $2ab^{}$

Tháng Mười Hai 10, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Rút gọn các biểu thức sau:
a. $2x.(2x-1)^{2}$ – $3x.(x+3).(x – 3)^{}$ – $4x. (x+1)^{2}$
b. $(a-b+c)^{2}$ – $(b-c)^{2}$ + $2ab^{}$ – $2ac^{}$
c. $(3x+1)^{2}$ – $2.(3x+1).(3x+5)^{}$ + $(3x+5)^{2}$
d. $4.(3^{2}+1)$ . $(3^{4}+1)$ . $(3^{8}+1)$ . $(3^{16}+1)$ . $(3^{32}+1)$

Comments ( 2 )

  1. kimoanh34
    kimoanh34
    10 Tháng Mười Hai, 2022 at 9:15 sáng
    Reply
    Giải đáp+Lời giải và giải thích chi tiết:
     a)
    2x(2x-1)^2-3x(x+3)(x-3)-4x.(x+1)^2
    =2x(4x^2-4x+1)-3x(x^2-9)-4x(x^2+2x+1)
    =8x^3-8x^2+2x-3x^3+27x-4x^3-8x^2-4x
    =(8x^3-3x^3-4x^3)+(-8x^2-8x^2)+(2x+27x-4x)
    =x^3-16x^2+25x
    b)
    (a-b+c)^2-(b-c)^2+2ab-2ac
    =a^2+b^2+c^2-2ab-2bc+2ac-(b^2-2bc+c^2)+2ab-2ac
    =a^2+b^2+c^2-2ab-2bc+2ac-b^2+2bc-c^2+2ab-2ac
    =a^2+(b^2-b^2)+(c^2-c^2)+(-2ab+2ab)+(-2bc+2bc)+(2ac-2ac)
    =a^2
    c)
    (3x+1)^2-2(3x+1)(3x+5)+(3x+5)^2
    =[(3x+1)-(3x+5)]^2
    =(3x+1-3x-5)^2
    =(-4)^2
    =16
    d)
    4(3^2+1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)
    =1/(2).8.(3^2+1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)
    =1/(2).(3^2-1)(3^2+1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)
    =1/(2).(3^4-1)(3^4+1)(3^8+1)(3^16+1)(3^32+1)
    =1/(2).(3^8-1)(3^8+1)(3^16+1)(3^32+1)
    =1/(2).(3^16-1)(3^16+1)(3^32+1)
    =1/(2).(3^32-1)(3^32+1)
    =1/(2).(3^64-1)
    =(3^64-1)/2

  2. lyly98
    lyly98
    10 Tháng Mười Hai, 2022 at 9:15 sáng
    Reply
    a)
    2x(2x – 1)^2 – 3x(x + 3)(x – 3) – 4x(x + 1)^2
    = 2x(4x^2 – 4x + 1) – 3x(x^2 – 9) – 4x(x^2 + 2x + 1)
    = 8x^3 – 8x^2 + 2x – 3x^3 + 27x – 4x^3 – 8x^2 – 4x
    = x^3 – 16x^2 + 25x
    b)
    (a – b + c)^2 – (b – c)^2 + 2ab – 2ac
    = a^2 + b^2 + c^2 – 2ab – 2bc + 2ca – (b^2 – 2bc + c^2) + 2ab – 2ac
    = a^2 + b^2 + c^2 – 2ab – 2bc + 2ca – b^2 + 2bc – c^2 + 2ab – 2ac
    = a^2
    c)
    (3x + 1)^2 – 2(3x + 1)(3x + 5) + (3x + 5)^2
    = (3x + 1 – 3x – 5)^2
    = (-4)^2
    = 16
    d)
    Đặt  A = 4(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^16 + 1)(3^32 + 1)
    ⇒ 2A = 8(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^16 + 1)(3^32 + 1)
    ⇒ 2A = (3^2 – 1)(3^2 + 1)(3^4 + 1)(3^8 + 1)(3^16 + 1)(3^32 + 1)
    ⇒ 2A = (3^4 – 1)(3^4 + 1)(3^8 + 1)(3^16 + 1)(3^32 + 1)
    ⇒ 2A = (3^8 – 1)(3^8 + 1)(3^16 + 1)(3^32 + 1)
    ⇒ 2A = (3^16 – 1)(3^16 + 1)(3^32 + 1)
    ⇒ 2A = (3^32 – 1)(3^32 + 1)
    ⇒ 2A = 3^64 – 1
    ⇒ A = (3^64 – 1)/2

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222-9+11+12:2*14+14 = ? ( )

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