3*1+3*2+3*3+,,,+3n= 3*(1+2+...+n)
=3*n(n+1)/2
cause 1+2+...+n=n(n+1)/2
Answer:
Carbon (C), nonmetallic chemical element in Group 14 (IVa) of the periodic table. Although widely distributed in nature, carbon is not particularly plentiful—it makes up only about 0.025 percent of Earth's crust—yet it forms more compounds than all the other elements combined.
Let's solve for x.<span><span><span>rs</span>x</span>=<span>14
</span></span>Step 1: Multiply both sides by x.<span><span>rs</span>=<span><span>14</span>x
</span></span>Step 2: Flip the equation.<span><span><span>14</span>x</span>=<span>rs
</span></span>Step 3: Divide both sides by 1/4.<span><span><span><span>14</span>x</span><span>14</span></span>=<span><span>rs</span><span>14</span></span></span><span>x=<span><span>4r</span>s
</span></span><u>Answer:</u><span>x=<span><span>4r</span><span>s</span></span></span>
