Question

помогите решить 7 и 9

Answer 1

7
AB=AC,AH_|_a,AH=3см,<ABH=<ACH=60
AB=AC=AH/sin<ACH=3:√3/2=6/√3=2√3см
<BAC=90
BC=AB√2=2√3*√2=2√6см
9
(x²-9x+8)/(x-4)-1≥0
(x²-9x+8-x+4)/(x-4)≥0
(x²-10x+12)/(x-4)≥0
x²-10x+12=0
x1+x2=10 U x1*x2=12
x1=2 u x2=6
x-4=0
x=4
           _                  +                  _                +
--------------[2]------------------(4)-----------[6]------------------
x∈[2;4) U [6;∞)