Đáp án:
Bài 1 =-50 bài 2 x = -13
Giải thích các bước giải:
[76 +123] -[23+76-12]= 76+123-23-76+12=100+12=112
[-5] +3.[-2] -[-20+5]=-5-6+20-5=-10+20-6=10-6=4
-125.7.2.8.[-5]=-250.7.(-40)=10000.7=70000
1-2+3-4+5-6+...+199-200=(-1).100=-100 (vì 2 số liên tiếp =-1 mà có 100 cặp)
136.[-15]+15.36+100.[-25]=15(-136+36)-2500=15.(-100)-2500=-1500-2500=-4000
-[456+125]-[44+127+357]= -456-125-44-127-357=-500-125-127-357=-625-484=-1109
134.[-62.56+70.23.78.15=134.(-3472+1883700)=134.1880228=251950552
1-6+11-16+21-26+...+91-96=(-5).10=-50
Bai 2
$a) 3x.2+[-15]=[-7].[-3]\Leftrightarrow 6x=21+15=36\Leftrightarrow x=6\\
b) -2.[4-x]+[-2] =22 \Leftrightarrow -8+2x=22+2=24\\
\Leftrightarrow 2x=24+8=32\Leftrightarrow x=16\\
c) (x+3).(x-1)=0\Leftrightarrow x+3=0, x-1=0\Leftrightarrow x=-3,x=1\\
d) -13-x=-[-25+8] \Leftrightarrow -13-x=-(-17)\\
\Leftrightarrow -x=17+13=30\Leftrightarrow x=-30\\
e) 2x-1=-27\Leftrightarrow 2x=-27+1=-26\Leftrightarrow x=-13$
