ax^2+bx=c型因式分解：12x^2-5x-2; 7x^2-6x-1; 5x^2+6xy-8y^2; 3a^2+8ab+4b^2
问题描述：
ax^2+bx=c型因式分解：12x^2-5x-2; 7x^2-6x-1; 5x^2+6xy-8y^2; 3a^2+8ab+4b^2
答
12x^2-5x-2
=(3x-2)(4x+1)
7x^2-6x-1
=(7x+1)(x-1)
5x^2+6xy-8y^2
=(5x-4y)(x+2y)
3a^2+8ab+4b^2
=(3a+2b)(a+2b)