Question

第一题 (2x+1)(3x-5)=(2x+1)(x+7) 第二题 25(2a+b)²=9(3a-b)²

Answer 1

(2x+1)(3x-5)=(2x+1)(x+7)

6x²-7x-5=2x²-15x+7

4x²+8x-12=0

x²+2x-3=0

(x+3)(x-1)=0

x+3=0 x-1=0

x1=-3

x2=1

25(2a+b)²=9(3a-b)²

25(2a+b)²-9(3a-b)²=0

(10a+5b-9a+3b)(10a+5b+9a-3b)=0

(a+8b)(19a+2b)=0

a+8b=0 19a+2b=0

∴a1=-8b

a2=-2/19