Bonjour ,
A) (-3x+5)²-(7x-8)²
25-30x+9x²-(49x²-112x+64)
25-30x+9x²-49x²+112x-64
-39+82x-40x²
=-40x²+82x-39
B)(-3x+5)²-(7x-8)²
(-3x+5-(7x-8))x(-3x+5+(7x-8))
(-3x+5-7x+8)x(-3x+5+7x-8)
=(-10x+13)x(4x-3)
C)(-3x3/4+5)²-(7+√5+2-8)²
(-9/4+5)²-(-1+√7)²
(11/4)²-(7-2√7+1)
121+16-(8-2√7)
121/16-8+2√7
=-7/16+2√7
D)(-3x+5)²-(7x-8)²=0
25-30x+9x²-(49x²-112x+64)=0
25-30x+9x²-49x²+112x-64=0
-39+82x-40x²=0
-40x²+82x-39=0
40x²-82x+39=0
x=-(-82) ±√(-82)²-4x40x39/2x40
x=82±√6724-6240/80
x=82±√484/80
x=82±22/80
x=82+22/80
x=82-22/80
x=13/10
x=3/4
x₁=3/4,x₂=3/10
