Toán Lớp 8: Rút gọn biểu thức sau:
(x-5)(x+5)-(2x+3)^2
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Toán Lớp 8: Rút gọn biểu thức sau:
(x-5)(x+5)-(2x+3)^2
Comments ( 2 )
=[x(x+5)-5(x+5)]-[(2x)^2+2.2x.3+3^2]
=(x^2+5x-5x-25)-(4x^2+12x+9)
=x^2-25-4x^2-12x-9
=-3x^2-12x-34