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3 years ago

Which term of the Ap: 3,8,13,18.......is 78?

Mathematics

1 answer:

Alex Ar [27]3 years ago

4 0

Answer:

$\bold{a_{16}=78}$

Step-by-step explanation:

$a_1=3,\ a_2=3+5=8,\ a_3=8+5=13,\ a_4=13+5=18\ \implies\ d=5\\\\a_n=a_1+(n-1)d\\\\a_n=3+(n-1)(5)\\\\a_n=3+5n-5\\\\a_n=5n-2\\\\ a_n=78\quad\implies\quad n=\,??\\\\78=5n-2\\\\78+2=5n\\\\5n=80\\\\n=16$

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LenaWriter [7]

Value of x is $\frac{-6}{13}\\$ and y is $\frac{36}{13}$

Solution set is ( $\frac{-6}{13}\\$ , $\frac{36}{13}$ )

Step-by-step explanation:

We need to solve the system of equations given.

$-2x+4y=12\\3x+7y= 18$

Solving

Let:

$-2x+4y=12\,\,eq(1)\\3x+7y=18\,\,eq(2)$

Multiply eq(1) by 3 and eq(2) by 2 and add both

$-6x+12y=36\\6x+14y=36\\-------\\26y=72\\y=\frac{72}{26}\\y=\frac{36}{13}$

Putting value of y in equation 1

$-2x+4y=12\\-2x+4(\frac{36}{13})=12\\-2x+\frac{144}{13}=12\\-2x=12-\frac{144}{13}\\-2x=\frac{12*13-144}{13}\\-2x=\frac{12}{13}\\x=\frac{-6}{13}\\$

So, value of x is $\frac{-6}{13}\\$ and y is $\frac{36}{13}$

Solution set is ( $\frac{-6}{13}\\$ , $\frac{36}{13}$ )

Keywords: System of equations

Learn more about system of equations at:

#learnwithBrainly

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3 years ago

Which term of the Ap: 3,8,13,18.......is 78?​

Which term of the Ap: 3,8,13,18.......is 78?