X1+x2=7,x1*x2=2
a)x1x2²+x1²x2=x1*x2*(x2+x1)=2*7=14
б)x1²+x2²=(x1+x2)²-2x1*x2=49-4=45
в)x1²*x2^4+x1^4*x2²=(x1*x2)²*(x2²+x1²)=4*45=180
г)x1³+x2³=(x1+x2)*(x1²-x1*x2+x2²)=7*(14-2)=7*12=84
д)x1³*x2^6+x1^6*x2³=(x1*x2)³(x2³+x1³)=8*84=672
е)x1^4+x2^4=(x1²+x2²)²-2(x1*x2)²=45²-2*2²=2025-8=2017
3х+15+4х=7х+15
7х=-15
х=-15/7=-2 1/7
<span>2*10^3+4*10^2+5*10+8=2458,
7*10^3+2*10^2+0*10+1=7201,
</span>9*10^2+3*10+3=933,
<span>4*10^3+1*10^2+1*10+4=4114
</span>