Toán Lớp 8: B1a,4x ²-4x+1-y ²
b, 4x ³-4x ²-9x+9
c,16x ²-2x-3
B2
a,(x+3) ²-(x-1)(x+1)=0
b,(x-2) ² -3x+6=0
GIUP MK VS
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Toán Lớp 8: B1a,4x ²-4x+1-y ²
b, 4x ³-4x ²-9x+9
c,16x ²-2x-3
B2
a,(x+3) ²-(x-1)(x+1)=0
b,(x-2) ² -3x+6=0
GIUP MK VS
Comments ( 1 )
Bài 1:
a, 4x ²-4x+1-y ² = (4x ² – 4x + 1) – y ²
= (2x – 1)² – y²
= (2x – 1 – y)(2x – 1 + y)
b, 4x ³ – 4x ² – 9x + 9 = (4x ³ – 4x ²) – (9x – 9)
= 4x(x – 1) – 9(x – 1)
= (x – 1)(4x – 9)
c, 16x ²-2x-3 = 16x² – 8x + 6x – 3
= (16x² – 8x) + (6x – 3)
= 8x(2x – 1) + 3(2x – 1)
= (2x – 1)(8x + 3)
Bài 2:
a, (x + 3 ) ² – (x – 1)(x + 1) = 0
↔ x² + 6x + 9 – x² + 1 = 0
↔ 6x + 10 = 0
↔ 6x = -10
→ x = -5/3
b, (x – 2)² – 3x + 6 = 0
↔ (x – 2)² – (3x + 6) = 0
↔ (x – 2)² – 3(x + 2) = 0
↔ (x – 2)(x – 2 – 3) = 0
⇔ (x – 2)(x – 5)
TH1 : x – 2 = 0
↔ x = 0 + 2 = 2
TH2: x – 5 = 0
↔ x = 0 + 5 = 5
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