1) 78.1 : 11 = 7.1
2)72.8:13 =5.6
3)65.8:14 =4.7
A/b=7/5
a-b=12
a=12+b
<u>12+b</u>= <u>7</u>
b 5
(12+b)*5=7b
60+5b-7b=0
-2b+60=0
-2b=-60
b=30
a=12+30=42
Ответ:30,42.
2cos^2 x +14cos x=3sin^2 x
2cos^2 x+14cos x-3*(1-cos^2 x)=0
2cos^2 x+14cos x-3+3cos^2 x=0
5cos^2 x+14cos x-3=0
cos x=t; 5t^2+14t-3=0; D1=7^2-5*(-3)=49+15=64=8^2; t1=(-7-8)/5=-3;t2=1/5;
cos x=-3 ili cos x=0,2
решений нет x=+-arccos0,2+2πn; n-celoe
------------------------------------
<span>1) 21*5*3*2=(21*3)*(5*2)=63*10=630</span><span> 2) 5*11*5*8*5=11*(5*5)*(5*8)=11*(25*40)=11*1000=11000</span><span> 3) 5*43*5*4=43*(5*5)*4=43*(25*4)=43*100=4300</span><span> 4) 6*5*2*7*2=(6*7)*2*(5*2)=(42*2)*10=84*10=840 </span><span>5) 125*4*25*8=(125*8)*(25*4)=1000*100=100000</span><span>6) </span><span>75*50*4*2=(75*4)*(50*2)=300*100=30000</span>