Question 477328
Let {{{ u }}} = the units digit
Let {{{ t }}} = the tens digit
given:
(1) {{{ t = u + 4 }}}
(2) {{{ t^2 + u^2  = 26 }}}
Substitute (1) into (2)
(2) {{{ (u + 4)^2 + u^2  = 26 }}}
(2) {{{ u^2 + 8u + 16 + u^2 = 26 }}}
(2) {{{ 2u^2 + 8u - 10 = 0 }}}
(2) {{{ u^2 + 4u - 5 = 0 }}}
(2) {{{ (u + 5)*(u - 1) = 0 }}} (I could see the factors)
{{{ u = 1 }}} (Not -5 because minus digits not allowed)
and
(1) {{{ t = u + 4 }}}
(1) {{{ t= 5 }}}
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The number is 51