Question

(2√3+1)(2√3-1); (√2-1)²+2√2; (√3+√5)²-2√15+(√3+√7)•(√3-√7); (√27-4)(3√3-4);

Answer 1

(2√3+1)(2√3-1)=12-1=11 ->formula de calcul prescurtat (a+b)(a-b)=a²-b²

(√2-1)²+2√2=2-2√2+1+2√2=3 ->formula de calcul prescurtat (a+b)²=a²+2ab+b²

(√3+√5)²-2√15+(√3+√7)•(√3-√7)=3+2√15+5-2√15+(3-7)
                                                  =8-4=4 ->cele doua formule, combinate

(√27-4)(3√3-4)
sau (3√3-4)(3√3-4)=27-24√3+16=43-24√3 ->formula de calcul prescurtat (a-b)²=a²-2ab+b²