Question

(7-4√3)(7+4√3)
(5√3-2√5)(5√3+2√5)
(√2x-2y)(√2x+2y)
(4√5-√15a)(4√5x-√15a)
Calculati , utilizand formula (a+b)(a-b)=a²-b²

Answer 1

[tex]a) (7-4 \sqrt{3})(7+4 \sqrt{3})= 7^{2}- (4 \sqrt{3})^{2}=49-48=1\\ b) (5 \sqrt{3}-2 \sqrt{5})(5 \sqrt{3}+2 \sqrt{5})= (5 \sqrt{3})^{2}- (2 \sqrt{5})^{2}=75-20=20\\ c) ( \sqrt{2}x- 2y)(\sqrt{2}x+2y)= (\sqrt{2}x)^{2} -(2y)^2=2 x^{2} -2y^2=2( x^{2} -y^2)\\ d) (4 \sqrt{5}- \sqrt{15}a)(4 \sqrt{5}+\sqrt{15}a)=(4 \sqrt{5})^2-(\sqrt{15}a)^2=80-15a^2[/tex]