Question

Calculati, utilizând forumulele de calcul prescurtat :
a) (3 - 2x)la puterea a 2 - (2x+5)(2x-5)+4(x-2) la puterea a 2

Answer 1

3la puterea a 2-2x3x2x+(2X)la puterea a doua-2Xla a doua+5 la a doua+4X-8;
x=ori
X=necunoscuta

Answer 2

a)(3-2x)²-(2x+5)(2x-5)+4(x-1)²
=[3²-2×3×2x+(-2x)²]-[(2x)²-5²]+4(x²-2×x×1+1²)
=(9-12x+4x²)-(4x²-25)+4(x²-2x+1)
=9-12x+4x²-4x²+25+4x²-8x+4
=4x²-20x+38
a=4
b=-20
c=38
∆=b²-4ac
∆=(-20)²-4×4×38
∆=400-(-608)
∆=400+608
∆=1008
x(1,2)=(-b±√∆)/2a
x(1,2)=[-(-20)±√1008]/2×4
x(1,2)=(20±12√7)/8
x(1)=(20+12√7)/8
x(1)=[4(5+3√7)]/8
x(1)=(5+3√7)/2
x(2)=(20-12√7)/8
x(2)=[4(5-3√7)]/8
x(2)=(5-3√7)/2