11/u-11/6u u=-1/6
66-11/6u
55/6u
55/6(-1/6)
55/-1
-55
d - разность арифметической прогрессии
d = an+1 - an
d = 4 - 8 = - 4
S15 = (2 * 8 + (15 - 1) * (-4))/2) * 15 = (16 - 56)/2) * 15 = -20 * 15 = -300
A^10*b^10*c^10...............
Y=x²<span>+bx+c для точкек А(6;4) и В(4;10)
4=6</span>²+6<span>b+c
10=4</span>²+4<span>b+c
</span><span>6b+c+32=0
</span><span>4b+c+6=0
</span>
<span>2b=-32+6
</span><span>b=-13
</span>4*(-13)+с+6=0
с=46
у=х²-13х+46
<span>y=kx+l для точкек А(6;4) и В(4;10):
</span>4=k*6+l , l=4- 6k
10=k*4+l , l=10- 4<span>k
</span> 4- 6k=10- 4<span>k
</span>2<span>k=-6
</span><span>k=-3
</span>l=4- 6<span>*(-3)=22
</span>у=-3х+22