Toán Lớp 8: Thực hiện các phép tính:
a) -7x^2(3x – 4y) b) (x – 3)(5x – 4)
c) (2x – 1)^2 d) (x + 3)(x – 3)
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Toán Lớp 8: Thực hiện các phép tính:
a) -7x^2(3x – 4y) b) (x – 3)(5x – 4)
c) (2x – 1)^2 d) (x + 3)(x – 3)
Comments ( 2 )
$=-21x^3+28x^2y$
b,
$=5x^2-4x-15x+12$
$=5x^2-19x+12$
$=(2x)^2-2.2x.1+1^2$
$=4x^2-4x+1$
d,
$(x+3)(x-3)$
$=x^2-3^2$
$=x^2-9$