Question

数学高手快来

Answer 1

x(x+1)+(2-x)(x+x)
= x²+x+4-x²
= x+4

(a+1/2b)(a-1/2b) - (3a-2b)(3a+2b)
= a²-1/4b² - (9a²-4b²)
= a²-1/4b² -9a²+4b²
= -8a² + 15/4b²

Answer 2

(1)=x^2+x+4-x^2=x+4
(2)=a^2-1/4b^2-9a^2+4b^2=-8a^2+15/4b^2