1.(х-3у)(х+3у)=х²-9у²;
4а(а+6)-(а-8)²=4а²+24а-(а²-16а+64)=3а²+40а-64;
2. 5m+5n-k(m+n)=5(m+n)-k(m+n)=(m+n)(5-k);
t³-t²-81t+81=(t³-t²)-(81t-81)=
=t²(t-1)-81(t-1)=(t-1)(t²-81)=
=(t-1)(t-9)(t+9);
16p²-(7-p)²=
=16p²-(49-14p+p²)=15p²+
14p-49
3. y= -4x+3
x= -1/2
y= 2+3=5
y=23
-4x+3=23
-4x= 20
x= -5
4. ср.скор= (62+54)/2=58км/ч
5. скидка 1344*0,04=53,76руб
без 1344+53,76=1397,76руб
<span>|х2+х-20|≤х2+х-20
</span>х2+х-20>0
d=1+80=81
X12=(-1+-9)/2=-5 4
(X-4)(X+5)>0
=========-5=======4=======
+++++++++ -------------- +++++++
1/при x<-5 x>4 |х2+х-20|=(х2+х-20)
2/x=(-5 4) |х2+х-20|=-(х2+х-20)
1/ х2+х-20≤х2+х-20
всегда равенство
2. -(х2+х-20)≤ х2+х-20
2x2+2x-40≥0
x2+x-20≥0
x=-5 4
ответx=(-oo -5]U[4 +oo)
<span>1) (1/9+b)^2 =1/81+2/9b+b</span>²<span>
,2) (k/2-t/5)^2=k</span>²/4-kt/5+t²/25<span>
3) (y+3 1/4)^2=y</span>²+6.5y+169/16<span>
4) (4 1/2+t)^2=81/4+9t+t</span>²
Делим 0,25а на 1,25в и равно это 0,2