Question

find n if an=20,a=10,d=2​

Answer 1

Solution:

n=2

Explaination:

If a=10

a×n=20

10×n=20

n=20/10

n=2/1

n=2

Answer 2

$\huge{\underline{\underline{\boxed{\sf{\purple{Answer࿐}}}}}}$

$\bf \: an = 20 \\ \\ \bf a = 10 \\ \\ \bf \: d = 2$

$\bf \: an = 20 \\ \\ \bf \implies a + (n - 1)d = 20 \\ \\ \bf \implies \: 10 + (n - 1)2 = 20 \\ \\ \bf \implies \: 10 + 2n - 2 = 20 \\ \\ \bf \implies \: 8 + 2n = 20 \\ \\ \bf \implies \: 2n = 20 - 8 \\ \\ \bf \implies \: 2n = 12 \\ \\ \bf \implies \: n = \cancel \frac{12}{2} \\ \\ \bf \implies \red{n = 6}$