Question 356634
81x^2=16
81x^2-16=0
(9x+4)(9x-4)=0
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9x=-4
x=-4/9
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9x=4
x=4/9
.
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8x^2-6x-5=0
8*-5=-40
Two factors of -40 whose sum is -6 are -10 and 4.
8x^2-10x+4x-5=0
2x(4x-5)+(4x-5)=0
(2x+1)(4x-5)=0 Factoring by grouping.
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2x=-1
x=-1/2
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4x=5
x=5/4
.
Ed