How do you solve $15x^2 + 26x + 8 = 0$ ?

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Answer 1 · 2016-01-04T15:51:03

Find a suitable split of the middle term, then factor by grouping to find:

$15x^2+26x+8 = (5x+2)(3x+4)$

Find two factors of $AC = 15*8 = 120$ whose sum is $B=26$ .

The pair $20$ , $6$ works:

$20 xx 6 = 120$

$20 + 6 = 26$

Then use these to split the middle term and factor by grouping:

$15x^2+26x+8$

$=(15x^2+20x)+(6x+8)$

$=5x(3x+4)+2(3x+4)$

$=(5x+2)(3x+4)$

How do you solve 15x^2 + 26x + 8 = 015x^2 + 26x + 8 = 0?