Toán Lớp 9: A=2√2-√50+2√8-√98 B=3×√1/3+1/2√12+√3 C=(2+√2/1+√2+3√3/√3)-1:1/√2+√3

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Toán Lớp 9:  A=2√2-√50+2√8-√98 B=3×√1/3+1/2√12+√3 C=(2+√2/1+√2+3√3/√3)-1:1/√2+√3

thudan · Answer

Hướng dẫn trả lời:     A = 2sqrt{2} - sqrt{50} + 2sqrt{8} - sqrt{98}   = 2sqrt{2} - sqrt{25cdot2} + 2sqrt{4cdot2} - sqrt{49cdot2}   = 2sqrt{2} - sqrt{5^2cdot2} + 2sqrt{2^2cdot2} - sqrt{7^2cdot2}   = 2sqrt{2} - 5sqrt{2} + 2cdot2sqrt{2} - 7sqrt{2}   = 2sqrt{2} - 5sqrt{2} + 4sqrt{2} - 7sqrt{2}   = - 6sqrt{2}   B = 3cdot sqrt{1/3} + 1/2cdot sqrt{12} + sqrt{3}   = sqrt{3^2cdot1/3} + 1/2cdot sqrt{4cdot3} + sqrt{3}   = sqrt{9cdot1/3} + 1/2cdot sqrt{2^2cdot3} + sqrt{3}   = sqrt{9/3} + 1/2cdot2sqrt{3} + sqrt{3}   = sqrt{3} + sqrt{3} + sqrt{3}   = 3sqrt{3}   C = ({2 + sqrt{2}}/{1 + sqrt{2}} + {3sqrt{3}}/{sqrt3}) - 1 &divide; 1/{sqrt{2} + sqrt{3}}   = ({sqrt{2}cdot(sqrt{2} + 1)}/{1 + sqrt{2}} + {3cdot sqrt{3}}/{1cdot sqrt3}) - 1 cdot {sqrt{2} + sqrt{3}}/1   = ({sqrt{2}cdot(1 + sqrt{2})}/{1 + sqrt{2}} + 3) - 1 cdot (sqrt{2} + sqrt{3})   = (sqrt{2} + 3) - (sqrt{2} + sqrt{3})   = sqrt{2} + 3 - sqrt{2} - sqrt{3}   = (sqrt{2} - sqrt{2}) + (3 - sqrt{3})   = 3 - sqrt{3}     Giải đáp:     A = - 6sqrt{2}   B = 3sqrt{3}   C = 3 - sqrt{3}

ngoclandiep · Answer

Xin gửi chủ tus ạ    Cho Mk xin xin c&acirc;u trả lời hay nha