Bài 1: Rút gọn a) A = √5+ √20- √45 b) B =3√5a - √20a + 4 √45a + √a (a ≥ 0) giúp mk gấp nha!
2 câu trả lời
`A=\sqrt{5}+\sqrt{20}-\sqrt{45}`
`A=\sqrt{5}+\sqrt{4.5}-\sqrt{9.5}`
`A=\sqrt{5}+2\sqrt{5}-3\sqrt{5}`
`A=0`
____________________________________________________
`B=3\sqrt{5a}-\sqrt{20a}+4\sqrt{45a}+\sqrt{a}` `(a>=0)`
`B=3\sqrt{5a}-\sqrt{4.5a}+4\sqrt{9.5a}+\sqrt{a}`
`B=3\sqrt{5a}-2\sqrt{5a}+12\sqrt{5a}+\sqrt{a}`
`B=13\sqrt{5a}+\sqrt{a}`
Đáp án: a) `A = 0`; b) `B =` `13`$\sqrt{5a}$ `+` $\sqrt{a}$
Giải thích các bước giải:
a) `A =` $\sqrt{5}$ `+` $\sqrt{20}$ `-` $\sqrt{45}$
`=` $\sqrt{5}$ `+` `2`$\sqrt{5}$ `-` `3`$\sqrt{5}$
`=` `3`$\sqrt{5}$ `-` `3`$\sqrt{5}$
`= 0`
b) `B =` `3`$\sqrt{5a}$ `-`$\sqrt{20a}$ `+` `4`$\sqrt{45a}$ `+` $\sqrt{a}$ (`a≥0`)
`=` `3`$\sqrt{5a}$ `-` `2`$\sqrt{5a}$ `+` `4.3`$\sqrt{5a}$ `+` $\sqrt{a}$
`=` `3`$\sqrt{5a}$ `-` `2`$\sqrt{5a}$ `+` `12`$\sqrt{5a}$ `+` $\sqrt{a}$
`=` `13`$\sqrt{5a}$ `+` $\sqrt{a}$
$#MintUwU$