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Category: Algebra

Question-176303

Question Number 176303 by infinityaction last updated on 16/Sep/22 Answered by cortano1 last updated on 16/Sep/22 $$\:\mathrm{let}\:\begin{cases}{{a}+{b}={x}}\\{{c}+{d}={y}}\end{cases}\Rightarrow{x}+{y}=\mathrm{2}\:;\:\mathrm{y}=\mathrm{2}−\mathrm{x} \\ $$$$\:\mathrm{M}=\mathrm{f}\left(\mathrm{x}\right)=\:\mathrm{x}\left(\mathrm{2}−\mathrm{x}\right)=\mathrm{2x}−\mathrm{x}^{\mathrm{2}} \:;\:\mathrm{x}\geqslant\mathrm{0} \\ $$$$\Rightarrow\mathrm{0}\leqslant\mathrm{f}\left(\mathrm{x}\right)\leqslant\mathrm{1} \\ $$$$\Rightarrow\mathrm{0}\leqslant\:\mathrm{M}\leqslant\mathrm{1} \\…

Proof-that-n-Z-n-2-1-0-mod-4-

Question Number 176279 by CrispyXYZ last updated on 15/Sep/22 $$\mathrm{Proof}\:\mathrm{that}\:: \\ $$$$\nexists{n}\in\mathbb{Z},\:{n}^{\mathrm{2}} +\mathrm{1}\equiv\mathrm{0}\left(\mathrm{mod}\:\mathrm{4}\right) \\ $$ Answered by mahdipoor last updated on 15/Sep/22 $${I}>\:{n}=\mathrm{2}{k}+\mathrm{1}\: \\ $$$$\Rightarrow{n}^{\mathrm{2}}…

a-b-9-ab-20-a-b-

Question Number 110728 by Study last updated on 30/Aug/20 $${a}+{b}=\mathrm{9}\:\:,\:\:{ab}=\mathrm{20}\:\:\:\:\:{a}−{b}=? \\ $$ Answered by som(math1967) last updated on 30/Aug/20 $$\left(\mathrm{a}−\mathrm{b}\right)^{\mathrm{2}} =\left(\mathrm{a}+\mathrm{b}\right)^{\mathrm{2}} −\mathrm{4ab} \\ $$$$\left(\mathrm{a}−\mathrm{b}\right)^{\mathrm{2}} =\mathrm{81}−\mathrm{80}…

a-b-c-d-are-unit-digits-whose-pairwise-sums-form-an-arithmetic-progression-Given-that-a-b-c-d-is-even-find-the-common-positive-difference-of-the-arithmetic-progression-

Question Number 110715 by Aina Samuel Temidayo last updated on 30/Aug/20 $$\mathrm{a},\mathrm{b},\mathrm{c},\mathrm{d}\:\mathrm{are}\:\mathrm{unit}\:\mathrm{digits}\:\mathrm{whose} \\ $$$$\mathrm{pairwise}\:\mathrm{sums}\:\mathrm{form}\:\mathrm{an}\:\mathrm{arithmetic} \\ $$$$\mathrm{progression}.\:\mathrm{Given}\:\mathrm{that}\:\mathrm{a}+\mathrm{b}+\mathrm{c}+\mathrm{d}\:\mathrm{is} \\ $$$$\mathrm{even},\:\mathrm{find}\:\mathrm{the}\:\mathrm{common}\:\mathrm{positive} \\ $$$$\mathrm{difference}\:\mathrm{of}\:\mathrm{the}\:\mathrm{arithmetic} \\ $$$$\mathrm{progression}. \\ $$ Commented…