Question

prove that .p(n) = 1+2+3+....+n =n(n+1)/2​

Answer 1

Answer:

It's solved in the given picture.

Answer 2

Step-by-step explanation:

< !DOCTYPE html > < html > < head > < meta name="viewport" content="width=device-width, initial-scale=1.0" > < title > Loading.. < /title > < style type="text/css" > div{ margin:160px 20px; width:100px; height:100px; background-color:red; color:white; border-radius:60px; border-color:red; font-size:20px; border-width:10px; border-style:solid; text-align:center; line-height:65px; animation-name:load; animation-duration:4s; animation-iteration-count:infinite; box-shadow:20px 20px black 20px 20px; } @keyframes load{ 0%{border-color:red;color:violet;} 25%{border-color:blue;color:yellow;} 50%{border-color:green;color:green;} 75%{border-color:yellow;color:blue;} 90%{border-color:violet;color:white;} 100%{border-color:red;color:violet;} } < /style > < /head > < body > < center > < div > < p > hiii.. < /p > < /div > < /center > < /body > < /html >

< !DOCTYPE html > < html lang="en" > < head > < title > CUBE < /title > < /head > < body > < div class="container" > < div id="cube" > < div class="front" > < /div > < div class="back" > ❣️ < /div > < div class="right" > ❤️ < /div > < div class="left" > < /div > < div class="top" > HELLO < /div > < div class="bottom" > HELLO < /div > < /div > < /div > < style > body { padding-left: 30%; padding-top: 5%; } .container { width: 200px; height: 200px; position: relative; -webkit-perspective: 1000px; -moz-perspective: 1000px; } #cube { width: 100%; height: 100%; position: absolute; -webkit-transform-style: preserve-3d; -webkit-animation: rotatecube 10s infinite; -moz-transform-style: preserve-3d; -moz-animation: rotatecube 10s infinite; } #cube div { width: 200px; height: 200px; display: block; position: absolute; border: none; line-height: 200px; text-align: center; font-size: 50px; font-weight: bold; } @-webkit-keyframes rotatecube { 0% { -webkit-transform: rotateX(0deg) rotateY(360deg) rotateZ(90deg); } 25% { -webkit-transform: rotateX(90deg) rotateY(270deg) rotateZ(180deg); } 50% { -webkit-transform: rotateX(180deg) rotateY(180deg) rotateZ(0deg); } 75% { -webkit-transform: rotateX(270deg) rotateY(90deg) rotateZ(360deg); } 100% { -webkit-transform: rotateX(360deg) rotateY(0deg) rotateZ(270deg); } } @-moz-keyframes rotatecube { 0% { -moz-transform: rotateX(0deg) rotateY(360deg) rotateZ(90deg); } 25% { -moz-transform: rotateX(90deg) rotateY(270deg) rotateZ(180deg); } 50% { -moz-transform: rotateX(180deg) rotateY(180deg) rotateZ(0deg); } 75% { -moz-transform: rotateX(270deg) rotateY(90deg) rotateZ(360deg); } 100% { -moz-transform: rotateX(360deg) rotateY(0deg) rotateZ(270deg); } } .front { background: rgba(255,0,0,.5); } .back { background: rgba(0,255,0,.5); } .right { background: rgba(0,0,255,.5); } .left { background: rgba(0,255,255,.5); } .top { background: rgba(255,0,255,.5); } .bottom { background: rgba(255,255,0,.5); } #cube .front { -webkit-transform: rotateY(0deg ) translateZ( 100px ); -moz-transform: rotateY( 0deg ) translateZ( 100px ); } #cube .back { -webkit-transform: rotateX( 180deg ) translateZ( 100px ); -moz-transform: rotateX( 180deg ) translateZ( 100px ); } #cube .right { -webkit-transform: rotateY( 90deg ) translateZ( 100px ); -moz-transform: rotateY( 90deg ) translateZ( 100px ); } #cube .left { -webkit-transform: rotateY( -90deg ) translateZ( 100px ); -moz-transform: rotateY( -90deg ) translateZ( 100px ); } #cube .top { -webkit-transform: rotateX( 90deg ) translateZ( 100px ); -moz-transform: rotateX( 90deg ) translateZ( 100px ); } #cube .bottom { -webkit-transform: rotateX( -90deg ) translateZ( 100px ); -moz-transform: rotateX( -90deg ) translateZ( 100px ); } < /style > < /body > < /html >