Toán Lớp 7: A)3x²(2x² 5x + 1). b) (2x + 1)(4x² 2x+1) . c) (6x³y5-5xy + 12x³y2): 2xy²
A) 2a – 2b
C )x² + 10x + 25 c) 3x² + 3xy-2x-2y
d) x² + 7x – 8 giúp mk với
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Toán Lớp 7: A)3x²(2x² 5x + 1). b) (2x + 1)(4x² 2x+1) . c) (6x³y5-5xy + 12x³y2): 2xy²
A) 2a – 2b
C )x² + 10x + 25 c) 3x² + 3xy-2x-2y
d) x² + 7x – 8 giúp mk với
Comments ( 1 )
a)3{x^2}\left( {2{x^2} – 5x + 1} \right)\\
= 2{x^2}.3{x^2} – 5x.3{x^2} + 1.3{x^2}\\
= 6{x^4} – 15{x^3} + 3{x^2}\\
b)\left( {2x + 1} \right)\left( {4{x^2} – 2x + 1} \right)\\
= {\left( {2x} \right)^3} + {1^3}\\
= 8{x^3} + 1\\
c)\left( {6{x^3}{y^5} – 5xy + 12{x^3}{y^2}} \right):2x{y^2}\\
= 6{x^3}{y^5}:2x{y^2} – 5xy:2x{y^2} + 12{x^3}{y^2}:2x{y^2}\\
= 3{x^2}{y^3} – \frac{5}{{2y}} + 6{x^2}\\
A)2a – 2b = 2\left( {a – b} \right)\\
b){x^2} + 10x + 25 = {\left( {x + 5} \right)^2}\\
c)3{x^2} + 3xy – 2xy – 2y\\
= 3x\left( {x + y} \right) – 2y\left( {x + y} \right)\\
= \left( {x + y} \right)\left( {3x – 2y} \right)\\
d){x^2} + 7x – 8\\
= {x^2} + 8x – x – 8\\
= \left( {x + 8} \right)\left( {x – 1} \right)
\end{array}$