關於化簡求值已知10^x=3 10^y=2求10^2x-3y的值

關於化簡求值已知10^x=3 10^y=2求10^2x-3y的值


10^2x-3y
=10^2x÷10^3y
=(10^x)^2÷(10^y)^3
=3^2÷2^3
=9/8



先化簡,再求值:x2−y2x+y-2(x+y),其中x=3,y=-13.


原式=(x+y)(x−y)x+y-2(x+y)=x-y-2x-2y=-x-3y,當x=3,y=-13時,原式=-3-3×(-13)=-2.



先化簡再求值(X2-4/X2-4X+4 - X-2/X+2)÷X\X-2其中X=2√3-2


[(X^2-4)/(X^2-4X+4)-(X-2)/(X+2)]÷[X/(X-2)]=[(x-2)(x+2)/(x-2)^2-(x-2)/(x+2)]×(x-2)/x=[(x+2)/(x-2)-(x-2)/(x+2)]×(x-2)/x={[(x+2)^2-(x-2)^2/[(x-2)(x+2)]}×(x-2)/x=8x/[(x-2)(x+2)]}×(x-2)/x=8/(x+2)=8/(2…