x2+8x-4=0

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this can't be factored out, so you have to use the quadratic formula: (-b +/- the square root of b^2 - 4ac) / 2a a: 1 b: 8 c: -4 (-8 +/- the square root of 64 - 4(1)(-4)) / 2(1) (-8 +/- the square root of 64 + 16) / 2 (-8 +/- the square root of 80) / 2 two answers: (-8 + 8.94) / 2 = .47 (-8 - 8.94) / 2 = -8.47 plug them both in to the original equation: (.47)^2 + 8(.47) - 4 = .2209 + 3.76 - 4 = 0 (-8.47)^2 + 8(-8.47) - 4 = 71.74 + (-67.76) - 4 = 0 they both equal work out ( = 0 ), so the answer is: (x - .47)(x + 8.47) = 0 x = .47, -8.47