Menu Close

In-an-arithmetic-progression-the-sum-of-the-third-term-and-8th-term-is-49-and-the-sum-of-the-5th-and-9th-term-is-58-Find-the-first-term-and-the-common-difference-using-simultaneous-equations-




Question Number 101185 by Shazneen last updated on 01/Jul/20
In an arithmetic progression the sum of the third term and 8th term is 49 and the sum of the  5th and 9th term is 58.Find the first term and the common difference using simultaneous equations.
$${In}\:{an}\:{arithmetic}\:{progression}\:{the}\:{sum}\:{of}\:{the}\:{third}\:{term}\:{and}\:\mathrm{8}{th}\:{term}\:{is}\:\mathrm{49}\:{and}\:{the}\:{sum}\:{of}\:{the}\:\:\mathrm{5}{th}\:{and}\:\mathrm{9}{th}\:{term}\:{is}\:\mathrm{58}.{Find}\:{the}\:{first}\:{term}\:{and}\:{the}\:{common}\:{difference}\:{using}\:{simultaneous}\:{equations}. \\ $$
Answered by $@y@m last updated on 01/Jul/20
a+2d+a+7d=49 & a+4d+a+8d=58  2a+9d=49  2a+12d=58  _________          3d=9  d=3  2a+9×3=49  2a=49−27  2a=22  a=11
$${a}+\mathrm{2}{d}+{a}+\mathrm{7}{d}=\mathrm{49}\:\&\:{a}+\mathrm{4}{d}+{a}+\mathrm{8}{d}=\mathrm{58} \\ $$$$\mathrm{2}{a}+\mathrm{9}{d}=\mathrm{49} \\ $$$$\mathrm{2}{a}+\mathrm{12}{d}=\mathrm{58} \\ $$$$\_\_\_\_\_\_\_\_\_ \\ $$$$\:\:\:\:\:\:\:\:\mathrm{3}{d}=\mathrm{9} \\ $$$${d}=\mathrm{3} \\ $$$$\mathrm{2}{a}+\mathrm{9}×\mathrm{3}=\mathrm{49} \\ $$$$\mathrm{2}{a}=\mathrm{49}−\mathrm{27} \\ $$$$\mathrm{2}{a}=\mathrm{22} \\ $$$${a}=\mathrm{11} \\ $$
Commented by smridha last updated on 01/Jul/20
thats not true..  ans:  a=11 and d=3
$$\boldsymbol{{thats}}\:\boldsymbol{{not}}\:\boldsymbol{{true}}.. \\ $$$$\boldsymbol{{ans}}: \\ $$$$\boldsymbol{{a}}=\mathrm{11}\:\boldsymbol{{and}}\:\boldsymbol{{d}}=\mathrm{3} \\ $$
Commented by Rasheed.Sindhi last updated on 01/Jul/20
 $@y@m sir you′ve mistakenly  add instead to subtract...  Are you old  ′s@ty@m′?
$$\:\$@{y}@{m}\:{sir}\:{you}'{ve}\:{mistakenly} \\ $$$${add}\:{instead}\:{to}\:{subtract}… \\ $$$${Are}\:{you}\:{old}\:\:'{s}@{ty}@{m}'? \\ $$
Commented by $@y@m last updated on 01/Jul/20
������ Hurry makes worry. I had doubt on my solution and I though I will check it later when I am free. No. I am young Satyam. ������ But after updating app, I am not able to login as my recent account Satyam123.
Commented by bemath last updated on 01/Jul/20
hahaha....i′m young boy too
$$\mathrm{hahaha}….\mathrm{i}'\mathrm{m}\:\mathrm{young}\:\mathrm{boy}\:\mathrm{too} \\ $$
Answered by Dwaipayan Shikari last updated on 01/Jul/20
suppose a is first term d  is the common difference  so a+2d+a+7d=49   ⇒2a+9d=49      a+4d+a+8d=58⇒2a+12d=58  3d=9⇒d=3  a=11
$${suppose}\:{a}\:{is}\:{first}\:{term}\:{d}\:\:{is}\:{the}\:{common}\:{difference} \\ $$$${so}\:{a}+\mathrm{2}{d}+{a}+\mathrm{7}{d}=\mathrm{49}\:\:\:\Rightarrow\mathrm{2}{a}+\mathrm{9}{d}=\mathrm{49} \\ $$$$ \\ $$$$\:\:{a}+\mathrm{4}{d}+{a}+\mathrm{8}{d}=\mathrm{58}\Rightarrow\mathrm{2}{a}+\mathrm{12}{d}=\mathrm{58} \\ $$$$\mathrm{3}{d}=\mathrm{9}\Rightarrow{d}=\mathrm{3} \\ $$$${a}=\mathrm{11} \\ $$

Leave a Reply

Your email address will not be published. Required fields are marked *