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

Toán Lớp 8: Thu gọn biểu thức : A = (x – 2) . (x + 2) + (x – 3) . (x + 3) – x . (2x +1) – 4 B = (5a – b + 1) . (5a + b – 1) – 24 . (a + 1)^2 + b^2

Home/ Toán Lớp 8: Thu gọn biểu thức : A = (x – 2) . (x + 2) + (x – 3) . (x + 3) – x . (2x +1) – 4 B = (5a – b + 1) . (5a + b – 1) – 24 . (a + 1)^2 + b^2

Toán Lớp 8: Thu gọn biểu thức : A = (x – 2) . (x + 2) + (x – 3) . (x + 3) – x . (2x +1) – 4 B = (5a – b + 1) . (5a + b – 1) – 24 . (a + 1)^2 + b^2

Tháng Hai 14, 2023 Toán học 2 Comments 0 views

Toán Lớp 8: Thu gọn biểu thức :
A = (x – 2) . (x + 2) + (x – 3) . (x + 3) – x . (2x +1) – 4
B = (5a – b + 1) . (5a + b – 1) – 24 . (a + 1)^2 + b^2 – 1
C = (a + b + c) . (a + b – c) + (a + c + b) . (a + c – b)

Comments ( 2 )

  1. ngoclandiep
    ngoclandiep
    14 Tháng Hai, 2023 at 1:30 chiều
    Reply
    A = (x – 2) . (x + 2) + (x – 3) . (x + 3) – x . (2x +1) – 4
    =x^2-4+x^2-9-2x^2-x-4
    =(x^2+x^2-2x^2)+(-4-9-4)-x
    =  -x-17
    B = (5a – b + 1) . (5a + b – 1) – 24 . (a + 1)^2 + b^2 – 1
    =(5a – b + 1) . [5a -(-b+1)] – 24 . (a + 1)^2 + b^2 – 1
    =25a^2-(1-b)^2 – 24 . (a + 1)^2 + b^2 – 1
    =25a^2-(1-2b+b^2) – 24 . (a + 1)^2 + b^2 – 1
    =25a^2-1+2b-b^2 -24(a^2+2a+1)+ b^2 – 1
    =25a^2-1+2b-b^2 -24a^2-48a-24+ b^2 – 1
    =(25a^2-24a^2)+(-b^2 + b^2 )-48a+2b+(- 1-24-1)
    = a^2 -48a+2b   -26   
    C = (a + b + c) . (a + b – c) + (a + c + b) . (a + c – b)
    =(a+b+c)(a + b – c+a + c – b)
    =2a(a+b+c)
    =2a^2+2ab+2ac

  2. hothaibinh
    hothaibinh
    14 Tháng Hai, 2023 at 1:29 chiều
    Reply
    A=(x-2).(x+2)+(x-3).(x+3)-x.(2x+1)-4
    =x^2-2^2+x^2-3^2-2x^2-x-4
    =x^2-4+x^2-9-2x^2-x-4
    =(x^2+x^2-2x^2)-x+(-4-9-4)
    =-x-17
    B=(5a-b+1).(5x+b-1)-24.(a-1)^2+b^2-1
    =(5a)^2-b^2-1^2-24.(a^2-2a.1+1^1)+b^2-1
    =25a^2-b^2-1-24a^2+48a-24+b^2-1
    =(25a^2-24a^2)+(-b^2+b^2)+48a+(-24-1)
    =a^2+48a-25
    C=(a+b+c).(a+b-c)+(a+b+c).(a+c-b)
    =a^2+b^2-c^2+a^2-b^2+c^2
    =(a^2+a^2)+(b^2-b^2)+(-c^2+c^2)
    =2a^2
    $@ThanhTruc2008$

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

Thanh Hương

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