Toán Lớp 9: Rút gọn biểu thức:
a) (2√3-5√27+4√12):√3
b) √125-4√45+3√20-√80
c) 2√32-5√27-4√8+3√75
d) (√5-3)(√5+3) +6
e) (√12-2√5)√3 + √60
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 9: Rút gọn biểu thức:
a) (2√3-5√27+4√12):√3
b) √125-4√45+3√20-√80
c) 2√32-5√27-4√8+3√75
d) (√5-3)(√5+3) +6
e) (√12-2√5)√3 + √60
Comments ( 2 )
a) – 5\\
b) – 5\sqrt 5 \\
c)0\\
d)3\\
e)6
\end{array}\)
a)\left( {2\sqrt 3 – 5.3\sqrt 3 + 4.2.\sqrt 3 } \right):\sqrt 3 \\
= \dfrac{{\left( {2 – 15 + 8} \right)\sqrt 3 }}{{\sqrt 3 }}\\
= – 5\\
b)5\sqrt 5 – 4.3\sqrt 5 + 3.2\sqrt 5 – 4\sqrt 5 \\
= \left( {5 – 12 + 6 – 4} \right)\sqrt 5 \\
= – 5\sqrt 5 \\
c)2.4\sqrt 2 – 5.3\sqrt 3 – 4.2\sqrt 2 + 3.5\sqrt 3 \\
= 8\sqrt 2 – 8\sqrt 2 – 15\sqrt 3 + 15\sqrt 3 \\
= 0\\
d)\left( {\sqrt 5 – 3} \right)\left( {\sqrt 5 + 3} \right) + 6\\
= 5 – 9 + 6\\
= – 3 + 6 = 3\\
e)\left( {2\sqrt 3 – 2\sqrt 5 } \right).\sqrt 3 + 2\sqrt {15} \\
= 2.3 – 2\sqrt {15} + 2\sqrt {15} \\
= 6
\end{array}\)