x1+x2=2a-1
x1x2=4a-4
x1²+x2²
=(x1+x2)²-2x1x2
=(2a-1)²-2(4a-4)
=4a²-4a+1-8a+8
=4a²-12a+9
=25
a²-3a-4=0
(a-4)(a+1)=0
a=4 b=3
S=1/2*4*3=6
x1+x2=2a-1
x1x2=4a-4
x1²+x2²
=(x1+x2)²-2x1x2
=(2a-1)²-2(4a-4)
=4a²-4a+1-8a+8
=4a²-12a+9
=25
a²-3a-4=0
(a-4)(a+1)=0
a=4 b=3
S=1/2*4*3=6