Toán Lớp 8: tìm x
5x(12-5x)-(6x-3)(5-4x)
(5-2x)^2+5x(x-1)-(1-3x)^2
(2x-1)^3-8(x-3)(3+x)+12x(x-2)
(2x-7)^2-3(x-1)^2+(x+6)(6-x)
ai làm nhanh em cho trlhn vs 5* ạ
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Toán Lớp 8: tìm x
5x(12-5x)-(6x-3)(5-4x)
(5-2x)^2+5x(x-1)-(1-3x)^2
(2x-1)^3-8(x-3)(3+x)+12x(x-2)
(2x-7)^2-3(x-1)^2+(x+6)(6-x)
ai làm nhanh em cho trlhn vs 5* ạ
Comments ( 1 )
a)5x\left( {12 – 5x} \right) – \left( {6x – 3} \right)\left( {5 – 4x} \right)\\
= 60x – 25{x^2} – 30x + 24{x^2} + 15 – 12x\\
= – {x^2} + 18x + 15\\
b){\left( {5 – 2x} \right)^2} + 5x\left( {x – 1} \right) – {\left( {1 – 3x} \right)^2}\\
= 25 – 20x + 4{x^2} + 5{x^2} – 5x – 1 + 6x – 9{x^2}\\
= – 19x + 24\\
c){\left( {2x – 1} \right)^3} – 8\left( {x – 3} \right)\left( {3 + x} \right) + 12x\left( {x – 2} \right)\\
= 8{x^3} – 12{x^2} + 6x – 1 – 8\left( {9 – {x^2}} \right) + 12{x^2} – 24x\\
= 8{x^3} + 8{x^2} – 18x – 73\\
d){\left( {2x – 7} \right)^2} – 3{\left( {x – 1} \right)^2} + \left( {x + 6} \right)\left( {6 – x} \right)\\
= 4{x^2} – 28x + 49 – 3{x^2} + 6x – 3 + 36 – {x^2}\\
= – 22x + 82
\end{array}$