x is the number of adults and y is the number of children.
x + y = 12
<span>14x + 10y = 140
lets multiply the first equation by -10 and then add it to the second equation:
-10x - 10y = -120
</span>14x + 10y = <span>140
</span>-----------------------
4x + 0 = 20
x = 20/4
x = 5
then substitute in the original equation:
x + y = <span>12
</span>5 + y = <span>12
</span>y = 12 - 5
y = 7
therefore there were 5 adults and 7 children
2(n-2)=9
That's the answer. U just set it up as it is written
We have that
<span>sin x=2/9
we know that
sin</span>² x+cos² x=1---------> cos² x=1-sin² x-----> cos² x=1-(2/9)²
cos² x=1-(4/81)------> (81-4)/81-----> 77/81
cos x=√(77/81)
Sin 2x = 2 sin x cos x-------> 2*(2/9)*(√(77/81))----> (4/81)*√77---> 0.43
Sin 2x=0.43
so
cos² 2x=1-sin² 2x---------> 1-[0.43]²-----> 1-[0.1878]----> 0.81
cos² 2x=0.81-----------> cos 2x=0.9
tan 2x=sin 2x/cos 2x--------> tan 2x=0.43/0.9---------> tan 2x=0.48
the answers are
sin 2x=0.43
cos 2x=0.9
tan 2x=0.48
