Exercise 2: Recognizing the No-Solution Case — Possible Solution ==================================================================== GIVEN ------------------------------ 4x + 6y = 10 2x + 3y = 8 STEP 1: ELIMINATING x ------------------------------ Using the row operation R2 -> R2 - (1/2) R1 (since row 2's leading coefficient, 2, is half of row 1's leading coefficient, 4): New row 2, column 1: 2 - (1/2)(4) = 0 New row 2, column 2: 3 - (1/2)(6) = 0 New row 2, RHS: 8 - (1/2)(10) = 8 - 5 = 3 Resulting row: [0, 0 | 3] -- meaning 0x + 0y = 3. STEP 2: WHAT THIS ROW MEANS ------------------------------ 0x + 0y = 3 is never true, for any x or y whatsoever. Per this chapter's own classification, a row that's entirely zero on the left but nonzero on the right (here, 3) means this system has NO SOLUTION - this is the inconsistent case, not the infinite-solutions case (which would instead require the right-hand side to also come out to 0). STEP 3: THE GEOMETRIC PICTURE ------------------------------ Dividing the first equation by 2 gives 2x + 3y = 5, directly comparable to the second equation, 2x + 3y = 8. Both equations have the exact same left-hand side (the same slope, since they're the same coefficients up to scaling) but different right-hand sides - these are two distinct PARALLEL lines. Parallel, non-identical lines never intersect, which is exactly why there's no (x, y) pair that satisfies both equations at once. WHY THIS WORKS AS AN ANSWER ------------------------------ The elimination is carried out using this chapter's own row-operation procedure, the resulting all-zero-left/nonzero-right row is matched to the specific "no solution" case (not the superficially similar "infinite solutions" case) from this chapter's own classification, and the geometric explanation is grounded in comparing the two equations' actual coefficients rather than simply asserting the lines are parallel.