Explicație pas cu pas:
a) (√3x+√5)(√3x-√5)=[(√3x)²-√3x×√5+√5×√3x-(√5)²=3x²-5
b) (2x-√3)(2x+√3)=(2x)²+2x×√3-√3×2x-(√3)²=4x²-3
c) (x-√7)(x+√7)= x²+x√7-x√7-(√7)²= x²-7
d) (√2x-3√3)(√2x+3√3)=(√2x)²+√2x×3√3-3√3×√2x-(3√3)²=2x²-27
e) (1/3x-1/2)(1/3x+1/2)=(1/3x)²+1/3x×1/2-1/2×1/3x-(1/2)²= 1/9 x²-1/4
f) (2/3 a -1)(2/3 a +1)= (2/3 a)²+ 2/3- 2/3 -1²= 4/9 a² -1
g) (7/5 x +3/4 y)(7/5 x -3/4 y)= (7/5 x)²- 7/5 x × 3/4 y + 3/4 y ×7/5x -(3/4 y)²= 49/25 x² - 9/16 y²
h) (1/5 x +2/3 y)( 1/5 x-2/3 y)= (1/5 x)²- 1/5 x × 2/3 y + 2/3 y × 1/5 x -( 2/3 y)²= 1/25 x²- 4/9 y²
i) (3√2 x +1/7)(3√2x-1/7)= (3√2x)²- 3√2 x × 1/7 +1/7×3√2 x- (1/7)²= 18x²-1/49
j) (√2x -1/√2 y)( √2x+1/√2 y)=(√2x)²+ √2 x×1/√2 y-1/√2y× √2x- (1/√2y)²= 2x²-1/2 y²
