factorise 8x³+16x-9
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Answered by
4
Answer:
Step-by-step explanation:
8x³ + 16x - 9
= 8x³ + 16x - 8 - 1
= 8x³ - 1 + 16x - 8
= (2x)³ - (1)³ + 8 (2x - 1)
//we know that a³ - b³ = (a - b)(a² + ab + b²)
= (2x - 1)(4x²+2x+1) + 8(2x - 1)
= (2x - 1) (4x² + 2x + 1 + 8)
= (2x - 1)(4x² + 2x + 9)
Answered by
1
Answer:
(2x - 1)(4x² + 2x + 9)
Step-by-step explanation:
Just take a close look at function ... Something might "hit" your mind ... like
8 × 0.125 = 1 and 16 ÷ 2 = 8 and 9 - 9 = 0 ⇒ x = 0.5 is zero of the function
f(x) = 8x³ + 16x - 9
(8x³ + 16x - 9) ÷ (x - 0.5) = 8x² + 4x + 18
In fact, x = 0.5 is only one zero of the given function.
8x³ + 16x - 9 = (2x - 1)(4x² + 2x + 9)
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