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Toán Lớp 8: 1.Tính a, (3a+2)³ b, (m²-n.½)³ c, (x+1)³-x(x-2)²-1 d, (x+1)²-(x-1)²-3(x+1).1(x.1)

Home/ Toán Lớp 8: 1.Tính a, (3a+2)³ b, (m²-n.½)³ c, (x+1)³-x(x-2)²-1 d, (x+1)²-(x-1)²-3(x+1).1(x.1)

Toán Lớp 8: 1.Tính a, (3a+2)³ b, (m²-n.½)³ c, (x+1)³-x(x-2)²-1 d, (x+1)²-(x-1)²-3(x+1).1(x.1)

Nhã Trúc Tháng Mười Hai 9, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: 1.Tính
a, (3a+2)³
b, (m²-n.½)³
c, (x+1)³-x(x-2)²-1
d, (x+1)²-(x-1)²-3(x+1).1(x.1)

Comments ( 1 )

thienthanh
9 Tháng Mười Hai, 2022 at 11:31 chiều

Reply

a, (3a+2)^3=(3a)^3+3.(3a)^2 .2+3.3a.2^2+2^3

=27a^3+54a^2+36a+8

b, (m^2-1/2 n)^3=(m^2)^3-3.(m^2)^2 .1/2n + 3.m^2 .(1/2 n)^2 – (1/2 n)^3

=m^6- 3/2 m^4 n+ 3/4 m^2n^2 – 1/8 n^3

c, (x+1)^3-x(x-2)^2-1

=(x^3+3x^2+3x+1)-x(x^2-4x+4)-1

=x^3+3x^2+3x+1-x^3+4x^2-4x-1

=7x^2-x

d) (x+1)^3-(x-1)^2-3(x+1)(x-1)

=(x^3+3x^2+3x+1)-(x^2-2x+1)-3(x^2-1)

=x^3+3x^2+3x+1-x^2+2x-1-3x^2+3

=x^3-x^2+5x

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