Respuesta :

4x²-17x-42
=4(x²-17/4x)-42
=4[x²-17/4  x+(-17/8)²-(-17/8)²]-42
=4(x-17/8)²-289/64-42
=4(x-17/8)²-(289+2688)/64
=4(x-17/8)²-2974/64
=[(2x-34/8)²-(√2974/8)²]
=(2x-34/8  +(√2974/8))(2x-34/8-(√2974/8)
=[2x+(√2974-34)/8][2x-(√2974+34)/8]