factorise by splitting the middle term 5x²-16x-21
Answers
Answer:
Multiply the coefficient of the first term by the constant 5 • -21 = -105
Find two factors of -105 whose sum equals the coefficient of the middle term, which is -16 .
-105 + 1 = -104
-35 + 3 = -32
-21 + 5 = -16 That's it
Rewrite the polynomial splitting the middle term using the two factors found in step 2 above, -21 and 5
5x2 - 21x + 5x - 21
Add up the first 2 terms, pulling out like factors :
x • (5x-21)
Add up the last 2 terms, pulling out common factors :
1 • (5x-21)
Add up the four terms of step 4 :
(x+1) • (5x-21)
Which is the desired factorization
Final result :
(5x - 21) • (x + 1)
Answer:
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