Question

(√с-7√d)*(c+7√cd+49d)-(√c+7√d)*(c-7√cd+49d)

Answer 1

(√с-7√d)*(c+7√cd+49d) = (√с)^3 - (7√d)^3

(√c+7√d)*(c-7√cd+49d) = (√с)^3 + (7√d)^3

(√с)^3 - (7√d)^3 - (√с)^3 - (7√d)^3 = -2(7√d)^3 = -686d√d

Ответ: -686d√d

Answer 2

$(sqrt{c}-7sqrt{d})cdot(c+7sqrt{cd}+49d)-(sqrt{c}+7sqrt{d})cdot(c-7sqrt{cd}+49d)=(ccdotsqrt{c}+7sqrt{cd}cdotsqrt{c}+49dcdotsqrt{c}-ccdot7sqrt{d}-7sqrt{d}cdot7sqrt{cd}-7sqrt{d}cdot49d)-(ccdotsqrt{c}-7sqrt{cd}cdotsqrt{c}+49dcdotsqrt{c}+ccdot7sqrt{d}-7sqrt{d}cdot7sqrt{cd}+7sqrt{d}cdot49d)=$

$\(csqrt{c}+7sqrt{c^{2}d}+49dsqrt{c}-7csqrt{d}-49sqrt{cd^{2}}-343dsqrt{d})-(csqrt{c}-7sqrt{c^{2}d}+49dsqrt{c}+7csqrt{d}-49sqrt{cd^{2}}+343dsqrt{d})=(csqrt{c}+7csqrt{d}+49dsqrt{c}-7csqrt{d}-49dsqrt{c}-343dsqrt{d})-(csqrt{c}-7csqrt{d}+49dsqrt{c}+7csqrt{d}-49dsqrt{c}+343dsqrt{d})=$

$\csqrt{c}+7csqrt{d}+49dsqrt{c}-7csqrt{d}-49dsqrt{c}-343dsqrt{d}-csqrt{c}+7csqrt{d}-49dsqrt{c}-7csqrt{d}+49dsqrt{c}-343dsqrt{d}=(csqrt{c}-csqrt{c})+(7csqrt{d}-7csqrt{d}+7csqrt{d}-7csqrt{d})+(49dsqrt{c}-49dsqrt{c}-49dsqrt{c}+49dsqrt{c})+(-343dsqrt{d}-343dsqrt{d})=-686dsqrt{d}$