2.4x-2.1=2.72.4x=2.7+2.12.4x=4.8x=4.8÷2.4x=2
x²=64+x²-8x+168x=80x=10a²(a+1)+(a+1)=0(a+1)(a²+1)=0a²+1=0无解所以a=-1(k-1)/4-(2-k)/3=2两边乘123k-3-8+4k=247k=35k=5
