Question 1062860
The general form is:
{{{ y = mx + b }}}
{{{ m = -2.5 }}}
{{{ y = -2.5x + b }}}
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{{{ y = f(x) }}}
{{{ 8 = f(5) }}}
This is the point ( 5,8 ), so
{{{ y = -2.5x + b }}}
{{{ 8 = -2.5*5 + b }}}
{{{ 8 = -12.5 + b }}}
{{{ b = 20.5 }}}
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The equation is:
{{{ y = -2.5x + 20.5 }}}
{{{ f(1) = -2.5*1 + 20.5 }}}
{{{ f(1) = 18 }}}
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check:
does the line go through ( 5,8 ) ?
{{{ y = -2.5x + 20.5 }}}
{{{ 8 = -2.5*5 + 20.5 }}}
{{{ 8 = -12.5 + 20.5 }}}
{{{ 8 = 8 }}}
Does it go through ( 1,18 ) ?
{{{ 18 = -2.5*1 + 20.5 }}}
{{{ 18 = 18 }}}
OK