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Toán Lớp 8: Tìm x: a) 3(1 – 4x)(x – 1) + 4(3x + 2)(x + 3) = 38 b) 5(2x + 3)(x + 2) – 2(5x – 4)(x – 1) = 75 c) 2x² + 3(x – 1)(x + 1) = 5x(x + 1)²

Home/ Toán Lớp 8: Tìm x: a) 3(1 – 4x)(x – 1) + 4(3x + 2)(x + 3) = 38 b) 5(2x + 3)(x + 2) – 2(5x – 4)(x – 1) = 75 c) 2x² + 3(x – 1)(x + 1) = 5x(x + 1)²

Toán Lớp 8: Tìm x: a) 3(1 – 4x)(x – 1) + 4(3x + 2)(x + 3) = 38 b) 5(2x + 3)(x + 2) – 2(5x – 4)(x – 1) = 75 c) 2x² + 3(x – 1)(x + 1) = 5x(x + 1)²

Thu Giang Tháng Tám 17, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: Tìm x:
a) 3(1 – 4x)(x – 1) + 4(3x + 2)(x + 3) = 38
b) 5(2x + 3)(x + 2) – 2(5x – 4)(x – 1) = 75
c) 2x² + 3(x – 1)(x + 1) = 5x(x + 1)²

Comments ( 1 )

thudan
17 Tháng Tám, 2022 at 1:41 chiều

Reply

#huy

a) 3(1 – 4x)(x – 1) + 4(3x + 2)(x + 3) = 38

<=>(3-12x)(x-1)+(12x+8)(x+3)-38=0

<=>3x-3-12x^2+12x+12x^2+36x+8x+24-38=0

<=>59x-17=0=>x=17/59

b) 5(2x + 3)(x + 2) – 2(5x – 4)(x – 1) = 75

<=>(10x+15)(x+2)-(10x-9)(x-1)-75=0

<=>10x^2+20x+15x+30-10x^2+10x+8x-8-75=0

<=>53x-53=0=>x=1

c) 2x^2 + 3(x – 1)(x + 1) = 5x(x + 1)^2

<=>2x^2+3(x^2-1)-5x^2-5x=0

<=>-3-5x=0=>x=(-3)/5

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