= <u></u>= <u>3х³у² *(-2ху^4)²</u> = <u> 3х³у² * 4х²у^8</u> = 3х^5y^10
4 4
<u>
</u>
sin5x-sin3x=0
2sinxcos4x=0
1) sinx=0 , x =<span>πn, </span>
<span>2) cos4x=0, 4x=<span>π/2 +<span>πn, x=<span>π/8+<span>π/4n</span></span></span></span></span>
S8=85/64
q=-1/2
S8=a1(q^8 -1)/(q-1)
a1=S8(q-1)/(q^8 -1)
a1=(85/64(-1/2-1))/(1/256-1)
a1=(85/64(-1.5))/(-255/256)
a1=2