Answer:
Explanation:
hello :
9x²=64 means : 9x²-64 =64-64
9x²-64 =0
but : 9x²=(3x)² and 64 = 8²
use identity : a²-b² = (a-b)(a+b)
9x²-64 =0 means : (3x)²-8² = (3x-8)(3x+8)=0
3x-8=0 or 3x+8=0
3x=8 or 3x=-8
two roots : x= 8/3 or x= -8/3
See below
9x^2=64
Square root of both sides: 3x=8 and 3x=-8
Divide both sides by 3: x=8/3 and x=-8/3
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