Mathematics: The 10th term of an a.p is -27 and the 5th term is -12 .find the first term?

Fx=5x_ 7/I is a fowards number so say+1 and5x_7= youneed a second number it is2 when u = so 2...

The 10th term of an a.p is -27 and the 5th term - id102755085055, issaaamiaaa15

Ответ:

jholland03

18.01.2022

Step-by-step explanation:

$a_{10} = - 27... (Given) \\\\\therefore a + 9d = - 27...... (1)\\\\a_{5} = - 12... (Given) \\\\\therefore a + 4d = - 12.......(2)\\\\$

Subtracting equation (2) from equation (1)

$a + 9d-( a + 4d )= - 27-(-12)\\\\\therefore a +9d - a-4d = - 27+12\\\\\therefore 5d = - 15\\\\\therefore d = \frac {- 15}{5}\\\\\huge \orange {\boxed {\therefore d = -3}} \\\\$

Substituting d = - 3 in equation (1), we find:

$a + 9\times (-3)= - 27\\\\\therefore a - 27 = - 27\\\\\therefore a = 27- 27\\\\\huge \red {\boxed {\therefore a = 0}}\\\\$

Hence, first term is zero.

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The 10th term of an a.p is -27 and the 5th term is -12 .find the first term?

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