{ localUrl: '../page/5gd.html', arbitalUrl: 'https://arbital.com/p/5gd', rawJsonUrl: '../raw/5gd.json', likeableId: '3139', likeableType: 'page', myLikeValue: '0', likeCount: '1', dislikeCount: '0', likeScore: '1', individualLikes: [ 'KevinClancy' ], pageId: '5gd', edit: '1', editSummary: '', prevEdit: '0', currentEdit: '1', wasPublished: 'true', type: 'comment', title: '"I think it would be worthwhile to explicitly ca..."', clickbait: '', textLength: '145', alias: '5gd', externalUrl: '', sortChildrenBy: 'recentFirst', hasVote: 'false', voteType: '', votesAnonymous: 'false', editCreatorId: 'EricRogstad', editCreatedAt: '2016-07-18 01:29:05', pageCreatorId: 'EricRogstad', pageCreatedAt: '2016-07-18 01:29:05', seeDomainId: '0', editDomainId: 'AlexeiAndreev', submitToDomainId: '0', isAutosave: 'false', isSnapshot: 'false', isLiveEdit: 'true', isMinorEdit: 'false', indirectTeacher: 'false', todoCount: '0', isEditorComment: 'true', isApprovedComment: 'true', isResolved: 'false', snapshotText: '', anchorContext: 'We'll do an example to build our intuition before giving the proper definition of the principle\\. We'll provide yet another proof that\n$$ 1 + 2 + \\cdots + n = \\frac{n(n+1)}{2}$$\nfor all integers $n \\ge 1$\\. First, let's check the base case, where $n=1$:\n$$ 1 = \\frac{1(1+1)}{2} = \\frac{2}{2} = 1.$$\nThis is \\(fairly obviously\\) true, so we can move forward with the inductive step\\. The inductive step includes an assumption, namely that the statement is true for some integer $k$ that is larger than the base integer\\. For our example, if $k\\ge1$, we assume that\n$$1 + 2 + \\cdots + k = \\frac{k(k+1)}{2}$$\nand try to prove that\n$$ 1 + 2 + \\cdots + k + (k+1) = \\frac{(k+1)([k+1]+1)}{2}.$$\nTake our assumption and add $k+1$ to both sides:\n$$1+2+\\cdots + k + (k+1) = \\frac{k(k+1)}{2} + k + 1.$$\nNow the left\\-hand sides of what we know and what we want are the same\\. Hopefully the right\\-hand side will shake out to be the same\\. Get common denominators so that the right\\-hand side of the above equation is\n$$\\frac{k(k+1)}{2} + \\frac{2(k+1)}{2} = \\frac{(k+2)(k+1)}{2} = \\frac{(k+1)([k+1]+1)}{2}.$$\nTherefore,\n$$ 1 + 2 + \\cdots + k + (k+1) = \\frac{(k+1)([k+1]+1)}{2}$$\nas desired\\.', anchorText: 'and try to prove that', anchorOffset: '606', mergedInto: '', isDeleted: 'false', viewCount: '287', text: 'I think it would be worthwhile to explicitly call out that what's happening here is that we're replacing $n$ in the original equation with $k+1$.', metaText: '', isTextLoaded: 'true', isSubscribedToDiscussion: 'false', isSubscribedToUser: 'false', isSubscribedAsMaintainer: 'false', discussionSubscriberCount: '1', maintainerCount: '1', userSubscriberCount: '0', lastVisit: '', hasDraft: 'false', votes: [], voteSummary: 'null', muVoteSummary: '0', voteScaling: '0', currentUserVote: '-2', voteCount: '0', lockedVoteType: '', maxEditEver: '0', redLinkCount: '0', lockedBy: '', lockedUntil: '', nextPageId: '', prevPageId: '', usedAsMastery: 'false', proposalEditNum: '0', permissions: { edit: { has: 'false', reason: 'You don't have domain permission to edit this page' }, proposeEdit: { has: 'true', reason: '' }, delete: { has: 'false', reason: 'You don't have domain permission to delete this page' }, comment: { has: 'false', reason: 'You can't comment in this domain because you are not a member' }, proposeComment: { has: 'true', reason: '' } }, summaries: {}, creatorIds: [ 'EricRogstad' ], childIds: [], parentIds: [ 'mathematical_induction' ], commentIds: [], questionIds: [], tagIds: [], relatedIds: [], markIds: [], explanations: [], learnMore: [], requirements: [], subjects: [], lenses: [], lensParentId: '', pathPages: [], learnMoreTaughtMap: {}, learnMoreCoveredMap: {}, learnMoreRequiredMap: {}, editHistory: {}, domainSubmissions: {}, answers: [], answerCount: '0', commentCount: '0', newCommentCount: '0', linkedMarkCount: '0', changeLogs: [ { likeableId: '0', likeableType: 'changeLog', myLikeValue: '0', likeCount: '0', dislikeCount: '0', likeScore: '0', individualLikes: [], id: '17068', pageId: '5gd', userId: 'EricRogstad', edit: '1', type: 'newEdit', createdAt: '2016-07-18 01:29:05', auxPageId: '', oldSettingsValue: '', newSettingsValue: '' } ], feedSubmissions: [], searchStrings: {}, hasChildren: 'false', hasParents: 'true', redAliases: {}, improvementTagIds: [], nonMetaTagIds: [], todos: [], slowDownMap: 'null', speedUpMap: 'null', arcPageIds: 'null', contentRequests: {} }