Toán Lớp 8: a) (2x – 3y) (2x + 3y) b) (1 + 5a) (1 + 5a) c) (2a + 3b) (2a + 3b) Làm giúp mik nhé
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Toán Lớp 8: a) (2x – 3y) (2x + 3y) b) (1 + 5a) (1 + 5a) c) (2a + 3b) (2a + 3b) Làm giúp mik nhé
Comments ( 2 )
=(2x)^2-(3y)^2
=4x^2-9y^2
b) (1 + 5a) (1 + 5a)
=(1+5a)^2
=(1)^2+2(1)(5a)+(5a)^2
=1+10a+25a^2
=(2a+3b)^2
=(2a)^2+2(2a)(3b)+(3b)^2
=4a^2+12ab+9b^2