(let ((x 2) (y 5)) (let* ((x 6)(z (+ x y)))(* z x) (display z)(newline);)(display x)(newline)(display y))

(let ((x 2) (y 5)) (let* ((x 6)(z (+ x y)))(* z x) (display z)(newline);)(display x)(newline)(display y)) 1.given the function f(x) = 2x*2 +5x -7,find the values of:a) f(-2) b) f(4) c) f(x*2) d) (f(x))*2 e) f(x*2) -xf(x)2.let f(x) =1/2 (2*x (符号是二的x次方) +2*-x (二的-x次方))show that for any real values of x and y,f(x+y) +f (x-y) = 2f(x)f(y 5x(x-y)+2y(x-y) 化简:5(x-y)+2(x+y)-3(x-y) 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) （X+2Y)(5X-2Y) (x+2y)(5x-2y) 4x+2y-5x-y (2x-3y)-(5x-y) (2X-3y)-(5x-y) (x-y)^2+5(x-y)-14 (2x-5y)(3x+y) 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y) (2x+y)²+(x+3y)(x-3y)-x(5x+8y)因式分解 [2(x-y)^5-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2[2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2 [(x+2y)(x-2y)-(2x-y)^2+(3x-y))2x-5y)]/(-x)我急用 [(x+2y)(x-2y)-(2x-y)²+(3x-y(2x-5y)]/(-x)的解答 [(x+2y)^2-(x-y)(x+2y)-5y^2]÷(2y)