Đáp án:
a) x² - 64
= x² - 8²
= (x - 8)(x + 8)
b) (x + y)² - x²
= (x + y - x)(x + y + x)
= y(2x + y)
c) (3x - 1)² - 16
= (3x - 1)² - 4²
= (3x - 1 - 4)(3x - 1 + 4)
= (3x - 5)(3x + 5)
d) 4x² + 4x + 1
= (2x)² + 2.2x + 1²
= (2x + 1)²
e) -x² + 10x - 25
= - (x² - 10x + 25)
= - (x² - 2.5.x + 5²)
= - (x - 5)²
f) x³ + 6x²y + 12xy² + 8y³
= x³ + 3.x².2y + 3.x.(2y)² + (2y)³
= x³ + 3.x².2y + 3.x.4y² + (2y)³
= (x + 3)³
g) x³ - 9x . (x + 3) - 27
= - (x³ + 9x² + 27x + 27)
= - (x³ + 3.x².3 + 3.x.3² + 3³)
= - (x + 3)³
h) 9x² - 25
= (3x)² - 5²
= (3x - 5)(3x + 5)
i) -1 + x²
= - (1 - x²)
= - (1² - x²)
= - (1 - x)(1 + x)
@Yết gửi bạn nhé~~
HỌC TỐT~~
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