已知x加3的绝对值等于（2x加y）的平方的相反数,求（4分之3）乘x的平方减3y加（4分之1）乘x的平方加y.

∣x + 3∣ = -(2x + y)^2 ,∵∣x + 3∣》0 ,且 -(2x + y)^2《 0 ,∴∣x + 3∣ = (2x + y)^2 = 0 ,∴x = -3 ,y = 6∴(3/4)(x^2 - 3y) + (1/4)(x^2 + y) = (3/4)·(-9) + (1/4)·15 = -3