Đáp án:
$1)$ `(√2x + (5√2)/4y - √((17y)/8)).(√2x + (5√2)/4y + √((17y)/8))`
$2)$ `(x - (3√2)/4y - √((25y)/8)).(x - (3√2)/4y - √((25y)/8))`
Giải thích các bước giải:
$1) 2x² +5xy +y²$
`= (√2x)² +2.√2x.(5√2)/4y +(5√2)/4y)² -(5√2)/4y)² +y²`
`= (√2x + (5√2)/4y)² - ((17y)/8)`
`= (√2x + (5√2)/4y - √((17y)/8)).(√2x + (5√2)/4y + √((17y)/8))`
$2) x² -3xy -2y²$
`= (x)² -2.x.(3√2y)/4 +(3√2)/4y)² -(3√2)/4y)² -2y²`
`= (x - (3√2)/4y)² - (25y)/8`
`= (x - (3√2)/4y - √((25y)/8)).(x - (3√2)/4y - √((25y)/8))`
Bạn áp dụng theo HĐT (a ±b)² -c² = (a ±b -c).(a ±b +c)!
