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

Toán Lớp 8: Bài 1: a)3ab(2a-5b-4ab) b)(3x-4)(5-2x) c)(4a+3b)mẫu 2 d)(xy-5z)(xy+5z) e)(2x-3) mẫu 2-(3x+1)(5x-2) Bài 2: tìm x biết: (6x-1)(2x-3

Toán Lớp 8: Bài 1:
a)3ab(2a-5b-4ab)
b)(3x-4)(5-2x)
c)(4a+3b)mẫu 2
d)(xy-5z)(xy+5z)
e)(2x-3) mẫu 2-(3x+1)(5x-2)
Bài 2: tìm x biết:
(6x-1)(2x-3)-4x(3x+2)=1

Comments ( 1 )

  1. a)3ab(2a -5b -4ab )
    =6a²b -15ab² -12a²b²
    b)( 3x-4 )(5-2x )
    = 15x -6x² -20 +8x
    c)(4a +3b)²
    =(4a)² +2.4a.3b +(3b)²
    =16a² +24ab +9b²
    d)(xy -5z )(xy +5z )
    =(xy)² -(5z)²
    =x²y² -25z²
    2>(6x -1 )(2x -3 ) -4x (3x +2 )=1
    ⇒12x² -18x -2x +3 -12² -8x =1
    ⇒(12x² -12x² )+(-18x – 2x-8x ) +3 =1
    ⇒ -28x +3 =1
    ⇒-28x= -2
    ⇒x =1/14
    <ĐLT>

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