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

Toán Lớp 8: a; (x³ + 4x² – x-4): (x+4) b; x²(x + y) +y²(x + y) + 2x²y + 2xy². c; (x + y)² + (x – y)² – 2(x+y)(x-y). d;

Tháng Chín 1, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: a; (x³ + 4x² – x-4): (x+4)
b; x²(x + y) +y²(x + y) + 2x²y + 2xy².
c; (x + y)² + (x – y)² – 2(x+y)(x-y).
d; (a + b)³ – (a – b)³ – 2b³ e; (x-y)(x+y)(x²+y²)(x⁴ + y⁴) dúp mik vs ạ

Comments ( 2 )

  1. phuongthaongoc
    phuongthaongoc
    1 Tháng Chín, 2022 at 8:27 sáng
    Reply
    ~ gửi bạn ~
    Lời giải và giải thích chi tiết:
    a) (x^3+4x^2−x−4):(x+4)
    = [x^2.(x+4)−(x+4)]:(x+4)
    = (x + 4).(x^2 – 1) : (x + 4)
    = x^2 – 1
    —————
    b) x^2.(x+y)+y^2.(x+y)+2x^2y+2xy^2
    =x^2.(x+y)+y^2.(x+y)+2xy.(x+y)
    = (x + y).(x^2 + y^2 + 2xy)
    = (x + y)^3
    —————-
    c) (x+y)^2+(x−y)^2−2.(x+y).(x−y)
    = (x+y)^2 – 2.(x + y).(x – y) + (x – y)^2
    = [(x + y) – (x – y)]^2
    = (x + y – x + y)^2
    = (2y)^2
    = 4y^2
    —————
    d) (a + b)^3 – (a – b)^3 – 2b^3
    = (a^3+3a^2b+3ab^2+b^3)−(a^3−3a^2b+3ab^2−b^3)−2b^3
    = a^3+3a^2b+3ab^2+ b^3−a^3+3a^2b−3ab^2+b^3−2b^3
    = (a^3−a^3)+(3a^2b+3a^2b)+(3ab^2−3ab^2)+(b^3+b^3−2b^3)
    = 0 + 6a^2b + 0 + 0
    = 6a^2b
    —————-
    e) (x−y).(x+y).(x^2+y^2).(x^4+y^4)
    = (x^2 – y^2).(x^2 + y^2).(x^4 + y4)
    = (x^4 – y^4).(x^4 + y^4)
    = x^8 – y^8

  2. tuyen98
    tuyen98
    1 Tháng Chín, 2022 at 8:26 sáng
    Reply
    a)
    (x^3 + 4x^2 – x-4) : (x+4)
    =  [ x^2 (x+4) – (x+4)] : (x+4)
    =  (x^2 – 1)(x+4) : (x+4)
    = x^2 – 1
    b)
    x^2 (x+y) + y^2 (x+y) + 2x^2y + 2xy^2
    = x^2 (x+y) + y^2 (x+y) + 2xy (x+y)
    = (x^2 + y^2 + 2xy)(x+y)
    =  (x+y)^2 . (x+y)
    =  (x+y)^3
    c)
    (x+y)^2 + (x-y)^2 – 2 (x+y)(x-y)
    =  [ (x+y) – (x-y)]^2
    =  (x+y – x + y)^2
    = (2y)^2
    =  4y^2
    d)
    (a+b)^3 – (a-b)^3 – 2b^3
    = (a^3 + 3a^2b + 3ab^2 + b^3) – (a^3 – 3a^2b + 3ab^2 – b^3) – 2b^3
    = a^3 + 3a^2b + 3ab^2+  b^3 – a^3 + 3a^2b – 3ab^2 + b^3 – 2b^3
    =  (a^3 – a^3) + (3a^2b + 3a^2b) + (3ab^2 – 3ab^2) + (b^3 + b^3-2b^3)
    = 6a^2b
    e)
    (x-y)(x+y)(x^2+y^2) (x^4+y^4)
    =  (x^2 – y^2)(x^2+y^2)(x^4+y^4)
    =  (x^4 – y^4)(x^4+y^4)
    =  x^8 – y^8

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

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