Question

Calculati punctele a,b,c (incepand cu 8b-8a......)

Answer 1

a)
a²-b²=108  ⇒(a-b)((a+b)=108  a+b=-9    (a-b)×(-9)=108  a-b=-12    b-a=12
8b-8a=8(b-a)=8×12=96

b)(x-5)(x²+5x+25)+(x²-9)²-(x-2√11)(x+2√11)-x(x+5)(x-5)=
=x³-5x²+5x²-25x+25x-125+x⁴-18x²+81-x²+44-x³+25x=
=-125+x⁴-18x²+81-x²+44+25x=
=x⁴-19x²+25x=
 =x(x³-19x+25)

c)1/√7 - 8/(√11-√7) ×√(√7-√11)²×1/√7=
=√7/7 (1- 8(√11+√7)/(11-7) ×(√7-√11)=
=√7/7 (1- 8(√11+√7)/4 ×(√7-√11)=
=√7/7 (1- 2(√11+√7)(√7-√11)=
=√7/7 (1- 2(7-11)=
=√7/7 (1+ 8)=
=9√7/7