解: ?$x-1=±3$? ?$x-1=3或x-1=-3$? 解得 ?${x}_{1}=4,{x}_{2}=-2$?
解: ?$x+3=±2$? ?$x+3=2或x+3=-2$? 解得 ?${x}_{1}=-1,{x}_{2}=-5$?
解: ?$(3x+2)2=7$? ?$3x+2=±\sqrt{7}$? ?${x}_{1}=\frac{-2+\sqrt{7}}{3},{x}_{2}=\frac{-2-\sqrt{7}}{3}$?
解: ?$(x+1)2=3$? ?$x+1=±\sqrt{3}$? ?${x}_{1}=-1+\sqrt{3},{x}_{2}=-1-\sqrt{3}$? 解:設(shè)這個(gè)紙盒的底面邊長(zhǎng)為x分米 ?$4x2= 25$? 解得 ?${x}_{1}=\frac{5}{2},{x}_{2}=-\frac{5}{2}$?(不符合題意,舍去) 答:這個(gè)紙盒的底面邊長(zhǎng)為 ?$\frac{5}{2}$?分米。
解: ?$x2-2x+1=1$? ?$(x-1)2=1$? ?$x-1=±1$? ?${x}_{1}=2,{x}_{2}=0$?
解: ?$x2-8x+16=4$? ?$(x-4)2=4$? ?$x-4=±2$? ?${x}_{1}=6,{x}_{2}=2$? 解: ?$x2+4x+4=9$? ?$(x+2)2=9$? ?$x+2=±3$? ?${x}_{1}=1,{x}_{2}=-5$?
解: ?$x2+6x+9=25$? ?$(x+3)2=25$? ?$x+3=±5$? ?${x}_{1}=2,{x}_{2}=-8$?
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