b,\(\sqrt{16\left(x+1\right)}-\sqrt{9\left(x+1\right)}+\sqrt{4\left(x+1\right)}-16\sqrt{x+1}=0\) (dk \(x\ge-1\)

\(\Leftrightarrow\sqrt{x+1}\left(4-3+2-16\right)=0\)

\(\Leftrightarrow\sqrt{x+1}.-13=0\)

\(\Leftrightarrow x=-1\)

A = ((20 + 1) . 20 : 2) . 2 = 420

B = (25 + 20) . 6  : 2 = 135

C = ( 33 + 26) . 8 : 2 = 236

D = (1 + 100) .100 : 2 = 5050

Toán lướp 9 dễ như vậy à bạn

2.

A=\(\sqrt{\sqrt{\left(\sqrt{16}-\sqrt{12}\right)^2}}-\sqrt{\sqrt{\left(\sqrt{16}+\sqrt{12}\right)^2}}\)

\(=\sqrt{4-2\sqrt{3}}-\sqrt{4+2\sqrt{3}}\)

\(=\sqrt{\left(\sqrt{3}-\sqrt{1}\right)^2}-\sqrt{\left(\sqrt{3}+\sqrt{1}\right)^2}\)

\(=\sqrt{3}-1-\left(\sqrt{3}+1\right)\)

\(=\sqrt{3}-1-\sqrt{3}-1\)

\(=-2\)

B= \(\sqrt{5-2\sqrt{2+\sqrt{\left(\sqrt{8}+\sqrt{1}\right)^2}}}\)

\(=\sqrt{5-2\sqrt{2+\sqrt{8}+1}}\)

\(=\sqrt{5-2\sqrt{3+2\sqrt{2}}}\)

\(=\sqrt{5-2\sqrt{\left(\sqrt{2}+\sqrt{1}\right)^2}}\)

\(=\sqrt{5-2\sqrt{2}-2}\)

\(=\sqrt{3-2\sqrt{2}}\)

\(=\sqrt{\left(\sqrt{2}-\sqrt{1}\right)^2}\)

\(=\sqrt{2}-1\)

=17.527864045

\(x=\dfrac{\sqrt{28-16\sqrt{3}}}{\sqrt{3}-1}=\dfrac{\sqrt{4}\sqrt{7-4\sqrt{3}}}{\sqrt{3}-1}\)

\(=\dfrac{2\sqrt{4-4\sqrt{3}+3}}{\sqrt{3}-1}=\dfrac{2\sqrt{\left(2-\sqrt{3}\right)^2}}{\sqrt{3}-1}\)

\(=\dfrac{2\left(2-\sqrt{3}\right)}{\sqrt{3}-1}=\dfrac{4-2\sqrt{3}}{\sqrt{3}-1}=\dfrac{3-2\sqrt{3}+1}{\sqrt{3}-1}\)

\(=\dfrac{\left(\sqrt{3}-1\right)^2}{\sqrt{3}-1}=\sqrt{3}-1\)

B=(x⁶+3x⁵-2x³+x²+2x-1)²⁰¹⁸=(x⁶+x⁵+2x⁵+2x⁴-2x⁴-2x³+x²+2x+1-2)²⁰¹⁸

=[(x+1)x⁵+2x⁴(x+1)-2x³(x+1)+(x+1)²-2]²⁰¹⁸

mà ta có : x+1=\(\sqrt{3}-1+1=\sqrt{3}\)

=> B=\(\left[\sqrt{3}\left(x^5+2x^4-2x^3\right)+(\sqrt{3})^2-2\right]^{2018}\)

Ta có : x⁵+2x⁴-2x³=x³(x²+2x+1-3)=x³[(x-1)² -3]=x³(3-3)=0

=>B=\(\left[\sqrt{3}.0+3-2\right]^{2018}=1^{2018}=1\)

Vậy .....