What is the missing coefficient in the above expression? (3x2-4x+7)(-2x2+5x-9) = -6x4+23x3+______x2+71x-63

Question

0

650

2

Guest Jan 6, 2015

+33661

+5

Best Answer

$$(3x^2-4x+7)(-2x^2+5x-9)=-6x^4+23x^3-61x^2+71x-63$$

Think of this as:

$$3x^2(-2x^2+5x-9)-4x(-2x^2+5x-9)+7(-2x^2+5x-9)$$

Then multiply the 3x² by all the terms inside the brackets; do the same for the -4x and the +7; then collect like terms together.

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Alan Jan 7, 2015

Alan · Answer 1 · 2015-01-07T09:58:37

$$(3x^2-4x+7)(-2x^2+5x-9)=-6x^4+23x^3-61x^2+71x-63$$

Think of this as:

$$3x^2(-2x^2+5x-9)-4x(-2x^2+5x-9)+7(-2x^2+5x-9)$$

Then multiply the 3x² by all the terms inside the brackets; do the same for the -4x and the +7; then collect like terms together.

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NotTheBestMathMaster · Answer 2 · 2015-01-06T04:59:45

I dont think that is possible all the numbers I put in = to at least somewhere around 4000 while the answer has to at least be 1,078