Question

\(57)\left(2x+5\right)\left(4x^2-10x+25\right)\)

\(59)\left(2x+3y\right)\left(4x^2-6xy+9y^2\right)\)

Answer 1

\(a,\left(2x+5\right)\left(4x^2-10x+25\right)\)

\(=\left(2x+5\right)\left[\left(2x\right)^2-2x.5+5^2\right]\)

\(=\left(2x\right)^3+5^3=8x^3+125\)

\(b,\left(2x+3y\right)\left(4x^2-6xy+9y^2\right)\)

\(=\left(2x+3y\right)\left[\left(2x\right)^2-2x.3y+\left(3y\right)^2\right]\)

\(=\left(2x\right)^3+\left(3y\right)^3=8x^3+27y^3\)

Answer 2

57) (2x + 5)(4x² - 10x + 25)

= 2x.4x² + 2x.(-10x) + 2x.25 + 5.4x² + 5.(-10x) + 5.25

= 8x³ - 20x² + 50x + 20x² - 50x + 125

= 8x³ + (-20x² + 20x²) + (50x - 50x) + 125

= 8x³ + 125

59) làm tương tự