4 Write sentences using the comparative. 1 My dad / old / my mumMy dad is older than my mum.2 A mouse / weak/ an elephant4 Running / boring / swimming5 A lion/ scary/mouse3 Maths / not hard / history6 Stephen/ angry/George​

Объяснение:

1.

a)5√2+2√32-√98=  5√2+2√(16*2)-√(49*2)= 5√2+2√(4²*2)-V(7²*2)=

=5√2+2*4√2-7√2=  5√2+8√2-7√2= 13√2-7√2=6√2

b)(4√3+2√21)*√3=4√3*√3+√27*√3=4√(3*3)=4√3²+√27*3)=4*3+√(81)=    =12+√9²=12+9=21

c)(√5-√3)²=5-2√5*√3+3=5-√(2*18)+3=5-2√(3²)*2)+3=8-2*3√2=8-6√2

2.

1/2√28              i    1/3√54

√(1/2)²*28)   i   √(1/3²)*54)

√(1/4*28)         i     √(1/9)*54)

         √7         >        √6

3.

(√10 +5)/(2+√10) =  (√10 +5)/(2+√10) *(2-√10)/(2-√10)=

=(√10+5)(2-√10) /(4-10)= (2√10-√10*√10+10-5√10)/(-6)=

=(-3√10-10+10)/(-6)=3√10/6=√10 / 2