Exercise ID383

Algebra → Progressions → Arithmetic progressions
[Level: ] [Number of helps: 1] [Number of pictures: 0] [Number of steps: 11] [Number of characters: 145]

The fourth member of the arithmetic series is 7, and the fifth is -5.
Determine the first member of the series!

$\phantom{\rule{0ex}{0ex}}$$d=-12\phantom{\rule{0ex}{0ex}}$ $\phantom{\rule{0ex}{0ex}}$ $\phantom{\rule{0ex}{0ex}}$${a}_{1}=7-3\left(-12\right)=7+36\phantom{\rule{0ex}{0ex}}$ $\phantom{\rule{0ex}{0ex}}$${a}_{1}=43\phantom{\rule{0ex}{0ex}}$
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${a}_{1}=43$