Toán Lớp 8: tìm x biết a)(x-1)^2-x(x+6)=10 b)4(x-2)^2-9(x+3)^2=0

Question

Toán Lớp 8:  tìm x biết  a)(x-1)^2-x(x+6)=10 b)4(x-2)^2-9(x+3)^2=0

maianh67 · Answer

a)(x-1)^2-x(x+6)=10   =)x^2-2x+1-x^2-6x=10   =)-8x-1=10   =)-8x=11   =)x=-11/8   b)4(x-2)^2-9(x+3)^2=0   =)[2(x-2)]^2-[3(x+3)]^2=0   =)(2x-4-3x-9)(2x-4+3x+9)=0   =)(-x-13)(5x+5)=0   =)x=-13 hoac x=-1

bichquyenlien · Answer

Giải đáp:   a) x = -11/8    b)  ( left[  begin{array}{l}x = -13  x =-1 end{array}  right. )    Lời giải và giải thích chi tiết:    a)(x-1)^2-x(x+6)=10     x^2-2x+1-x^2-6x=10     -8x-1=10     -8x=11     x=-11/8     b)4(x-2)^2-9(x+3)^2=0     [2(x-2)]^2-[3(x+3)]^2=0     (2x-4-3x-9)(2x-4+3x+9)=0     (-x-13)(5x+5)=0    =>  ( left[  begin{array}{l}-x-13=0  5x+5=0 end{array}  right. )   =>  ( left[  begin{array}{l}-x=0+13  5x=0-5 end{array}  right. )   =>  ( left[  begin{array}{l}x = -13  5x=-5 end{array}  right. )   =>  ( left[  begin{array}{l}x=-13  x=-5:5 end{array}  right. )   =>  ( left[  begin{array}{l}x = -13  x =-1 end{array}  right. )