Toán Lớp 8: 1.x( x – 3) + ( x + 3)^2 = 2x( x – 5)+35
2.( 3x – 2)^2 + ( 2x + 3)^2=( 2x – 5).(9x + 1) – 5x^2-68
Mong mng giúp ạ. E cảm ơn
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Toán Lớp 8: 1.x( x – 3) + ( x + 3)^2 = 2x( x – 5)+35
2.( 3x – 2)^2 + ( 2x + 3)^2=( 2x – 5).(9x + 1) – 5x^2-68
Mong mng giúp ạ. E cảm ơn
Comments ( 2 )
Giải đáp:
Lời giải và giải thích chi tiết:
1/ x(x-3) +( x – 3)^2 =2x(x-5)+35
⇔ x^2 -3x +x^2 -6x +9 = 2x^2-10x +35
⇔ 2x^2 -9x +9 = 2x^2 -10x +35
⇔ 2x^2 -2x^2 -9x +10x = 35 -9
⇔ x = 26
2/ ( 3x – 2)^2 + ( 2x + 3)^2=( 2x – 5).(9x + 1) – 5x^2-68
⇔ (9x^2-12x+4)+(4x^2+12x+9)=18x^2-43x-5-5x^2-68
⇔ 43x=-86
⇔ x=-2
$\text{1) x(x – 3) + (x + 3)² = 2x(x – 5) + 35}$
$\text{⇔ x² – 3x + x² + 6x + 9 = 2x² – 10x + 35}$
$\text{⇔ x² + x² – 2x² – 3x + 6x + 10x = 35 – 9}$
$\text{⇔ 13x = 26}$
$\text{⇔ x = 2}$
$\text{Vậy x = 2}$
$\text{b) (3x – 2)² + (2x + 3)² = (2x – 5)(9x + 1) – 5x² – 68}$
$\text{⇔ 9x² – 12x + 4 + 4x² + 12x + 9 = 18x² + 2x – 45x – 5 – 5x² – 68}$
$\text{⇔ 13x² + 13 = 13x² – 43x – 73}$
$\text{⇔ 13x² – 13x² + 43x = -73 – 13}$
$\text{⇔ 43x = -86}$
$\text{⇔ x = -2}$
$\text{Vậy x = -2}$
$\textit{Ha1zzz}$